UC-NRLF 


OF 

UJUVER? 

or 


2EYSICS 


THE   INFLUENCE 


OF   A 


MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA 
OF   IRON   AND  TITANIUM 


BY 

ARTHUR   S.  KING 


WASHINGTON,   I).  C. 
PUBLISHED  BY  THE/ CARNEGIE  INSTITUTION-  OF 


THE   INFLUENCE 


OF  A 


MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA 
OF   IRON  AND  TITANIUM 


BY 

ARTHUR   S.  KING 


WASHINGTON,  D.  C. 

PUBLISHED  BY  THE/ CARNEGIE  INSTITUTION  OF  WASHINGTON 

1912 


CARNEGIE  INSTITUTION  OF  WASHINGTON 

PUBLICATION  No.  153 

PAPERS  OF  THE  MOUNT  WILSON  SOLAR  OBSERVATORY,  VOL.  II,  PART  I 
GEORGE  K.  HALE,  Director 


PRESS   OF   J.   B.   LIPPINCOTT   COMPANY 
PHILADELPHIA,   PA. 


QCL75 


PHYSICS 
LIBRARY 


TABLE    OF    CONTENTS. 


PAGE 

INTRODUCTION i 

THEORY  AND  FORMER  INVESTIGATIONS. 

1.  GENERAL  . : 3 

2.  POSSIBLE  RELATION  BETWEEN  ZEEMAN  SEPARATION  AND  PRESSURE  DISPLACEMENT 5 

3.  FORMER  INVESTIGATIONS  OF  THE  ZEEMAN  EFFECT  FOR  IRON 7 

4.  FORMER  INVESTIGATIONS  OF  THE  ZEEMAN  EFFECT  FOR  TITANIUM 8 

APPARATUS   AND  METHODS. 

i.  SPARK  APPARATUS 9 

3.  THE  ELECTRO-MAGNET n 

3.  THE  SPECTROGRAPH 13 

4.  PHOTOGRAPHIC  METHODS 16 

5.  MEASUREMENT  OF  MAGNETIC  FIELD 16 

6.  METHODS  OF  MEASUREMENT  AND  REDUCTION 17 

EXPLANATION  OF  THE  TABLES. 

1.  WAVE-LENGTHS 19 

2.  INTENSITY .19 

3.  CHARACTER  OF  SEPARATION 19 

4.  WEIGHT 20 

5.  VALUES  OF  AX 21 

6.  VALUES  OF  AX/X2 21 

TABLE   i,  MEASUREMENTS  OF  ZEEMAN   EFFECT  FOR  IRON 22 

TABLE   2,  MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  TITANIUM 35 

TYPES  OF   SEPARATION. 

1.  UNAFFECTED  LINES 44 

2.  TRIPLETS 44 

3.  QUADRUPLETS 45 

4.  QUINTUPLETS 45 

5.  SEXTUPLETS .  45 

6.  SEPTUPLETS 46 

7.  OCTUPLETS 46 

8.  NONETS 46 

9.  MORE  COMPLEX  TYPES 46 

RELATION  OF  SEPARATIONS  TO  THE  NORMAL  INTERVAL. 

1.  SUMMARIES  FOR  VARIOUS  TYPES 47 

2.  DISCUSSION  OF  RELATIONS  TO  NORMAL  INTERVAL 49 

POSSIBLE  RELATIONS  BETWEEN  LINES   AS  INDICATED  BY  THE  ZEEMAN   EFFECT 50 

CASES  OF  DISSYMMETRY 51 

LAW  OF  CHANGE  OF  THE  AVERAGE  SEPARATION  OF  THE  ^-COMPONENTS  WITH  THE  WAVE-LENGTH S3 

THE  EFFECT  OF  THE  MAGNETIC  FIELD  UPON  ENHANCED  LINES 54 

COMPARISON  OF  THE  RESULTS  FOR  THE  ZEEMAN  EFFECT  AND  FOR  PRESSURE  DISPLACEMENT 56 

SUMMARY   OF  RESULTS 64 

BIBLIOGRAPHICAL  REFERENCES 65 

iii 


INTRODUCTION. 


The  investigation  of  which  an  account  is  given  in  the  following  pages  was  carried  out  during  the  year 
1910  in  the  Pasadena  laboratory  of  the  Solar  Observatory.  The  object  was  to  obtain  as  complete  data  as 
possible  concerning  the  influence  of  a  magnetic  field  on  the  spectra  of  iron  and  titanium  through  a  con- 
siderable range  of  wave-length,  and  to  present  this  in  such  form  as  would  be  useful  for  reference  in  con- 
nection with  questions  concerning  the  effect  of  a  magnetic  field  on  the  spectrum  lines,  such  as  those  arising 
in  investigations  on  sun-spots,  as  well  as  for  comparison  with  the  known  phenomena  of  the  Zeeman  effect  for 
spectra  other  than  those  of  iron  and  titanium.  The  tables  are  designed  to  give  an  accurate  description 
of  all  lines  between  \37oo  and  X 6700,  so  far  as  it  has  been  possible  to  photograph  them.  The  measure- 
ments of  magnetic  separations  for  each  spectrum  through  this  range  show  clearly  the  degree  in  which 
the  separation  changes  with  the  wave-length.  The  complex  types  as  well  as  the  simpler  are  studied  with 
reference  to  the  prevalence  of  a  fundamental  interval  between  the  components.  Numerous  cases  are 
noted  of  the  recurrence  of  certain  types  of  separation,  and  while  the  search  for  series  relations  in  these 
many-lined  spectra  has  not  proved  fruitful,  the  descriptions  of  the  type  of  separation  show  whether 
certain  lines  are  possibly  connected,  or  whether  they  unquestionably  arise  from  different  radiating  par- 
ticles. A  few  cases  of  dissymmetry  among  components  are  given  in  the  tables.  It  has  been  possible, 
by  reason  of  the  large  amount  of  material  collected,  to  make  a  detailed  comparison  between  the  Zeeman 
separation  and  the  displacement  of  lines  produced  by  pressure  around  a  light  source,  and  it  is  shown  to 
what  degree  a  correspondence  exists.  The  reproductions  of  spectra  which  are  given  are  of  selected  regions 
showing  the  various  types  of  magnetic  separation  and  the  behavior  of  groups  of  lines  which  are  of  special 
interest  in  other  investigations  on  these  spectra. 

The  desirability  of  making  the  material  as  complete  as  possible  has  necessitated  photographing 
the  weaker  lines  in  these  two  spectra  so  far  as  they  were  obtainable,  a  condition  which  has  added  to  the 
labor  and  altered  to  some  extent  the  experimental  methods  that  would  have  been  used  for  the  stronger 
lines  alone.  The  tables  for  titanium  contain  all  but  the  weakest  of  those  lines  given  in  the  regular  lists 
of  arc  and  spark  lines.  As  much  can  not  be  claimed  for  iron,  however,  as  numerous  lines,  fairly  strong 
in  the  arc,  are  not  brought  out  by  the  spark  in  the  magnetic  field  even  with  an  exposure  of  many  hours. 
This  is  especially  true  of  lines  of  diffuse  appearance,  which  are  particularly  numerous  in  the  iron 
spectrum. 

The  results  of  a  number  of  investigations  on  the  Zeeman  effect  for  certain  parts  of  the  iron  spectrum 
have  been  published,  and  will  be  spoken  of  in  the  historical  summary  to  follow.  These  are  fragmentary, 
however,  with  some  discordances,  and  it  is  believed  that  there  is  little  real  duplication  in  the  present 
paper,  even  for  those  parts  of  the  spectrum  which  have  been  treated  to  some  extent  by  others. 


THEORY  AND  FORMER  INVESTIGATIONS. 

i.  GENERAL. 

It  is  not  the  purpose  of  the  author  to  give  here  in  any  detail  the  development  of  the  theory  of  the 
Zeeman  effect  or  to  summarize  at  length  the  many  investigations  which  have  led  to  the  present  state 
of  knowledge  regarding  the  phenomenon.  Several  such  accounts  have  appeared  in  publications  which 
are  usually  accessible.  Among  these  may  be  mentioned  the  memoir  of  Cotton  (i)*  (1899),  the  chapter 
by  Runge  in  Kayser's  Handbuch  der  Spectroscopie  (2)  (1902),  the  detailed  discussion  by  Voigt  (3)  (1908) 
in  connection  with  the  related  optical  phenomena,  and  the  brief  treatment  by  Lorentz  (4)  (1909)  in  his 
Columbia  Lectures.  Of  these  the  second  is  by  far  the  most  complete,  covering  fully  the  historical  devel- 
opment, methods  of  investigation,  and  the  theory  and  spectroscopic  results  contained  in  the  literature 
up  to  that  time.  For  the  purposes  of  the  present  paper,  we  shall  consider  the  points  in  the  theory  which 
apply  closely  to  the  results  of  this  investigation,  and  summarize  the  work  of  other  investigators  in  so 
far  as  their  results  relate  directly  to  those  of  the  present  research. 

The  later  work  on  the  Zeeman  phenomenon  has  been  concerned  largely  with  the  study  of  complex  and 
unusual  types  of  separation.  It  was  shown  during  the  earlier  investigations  by  Zeeman  (5) ,  Michelson  (6), 
Preston  (7),  Cornu  (8),  Becquerel  and  Deslandres  (9),  (10),  Ames,  Earhart  and  Reese  •("),  Reese  (12)  ,  and 
Kent  (13)  that  a  large  proportion  of  the  spectrum  lines  of  any  of  the  elements  that  have  been  examined 
are  split  into  more  than  three  components.  This  involved  an  extension  of  the  original  theory  of  Lorentz, 
which  satisfactorily  explained  the  triplet  separation,  in  which  two  components  are  given  by  the  light 
vibrations  in  a  plane  perpendicular  to  the  lines  of  magnetic  force,  these  showing  respectively  a  right- 
handed  and  a  left-handed  circular  polarization,  and  a  central  component  by  the  light  vibrations  paral- 
lel to  the  magnetic  force-lines.  Since  the  phenomenon  in  its  simplest  form  justified  taking  the  electron 
theory  as  the  basis  of  all  conceptions  of  the  action  of  the  magnetic  field  upon  spectra,  a  series  of  investi- 
gations, among  which  those  of  Lorentz  (14),  Larmor  (15),  Voigt  (16),  and  Robb  (17)  may  be  mentioned,  have 
greatly  extended  the  mathematical  theory,  both  for  radiation  in  general  and  for  the  explanation  of  the 
more  complex  forms  of  magnetic  separation.  Voigt  and  Robb  have  based  their  theory  on  the  idea  of 
mutually  connected  systems  of  electrons,  and  have  thus  been  able  to  account  for  many  of  the  more  com- 
plicated types  of  Zeeman  separation.  However,  both  the  nature  of  the  connections  and  the  way  the 
magnetic  field  effects  such  systems  are  but  imperfectly  explained. 

The  proportionality  of  separation  of  components  to  field-strength  has  been  worked  on  by  Reese  ("), 
Kent  ( 13) ,  Runge  and  Paschen  (18),  Farber  ( 19) ,  Weiss  and  Cotton  (20),  Paschen  ( 21) ,  and  Stettenheimer  (22), 
and  established  to  a  very  close  approximation.  The  law  enunciated  by  Preston  (23 )  that  the  character  of 
separation  and  distance  between  components  (measured  in  terms  of  change  of  vibration  frequency)  is  the 
same  for  corresponding  lines  in  the  series  of  Balmer,  Rydberg,  and  Kayser  and  Runge  has  been  investigated 
by  Reese  (12),  Kent  (13),  Runge  and  Paschen  (24),  Runge  and  Precht  (25),  Miller  (26),  and  Lohmann  (27). 
The  last  two  have  found  some  exceptions,  though  Runge  and  Paschen  observed  very  close  agreement  for 
the  series  lines  of  a  number  of  elements.  This  relation  has  frequently  been  used,  recently  by  Moore  (28) , 
in  an  attempt  to  find  series  among  spectra  containing  many  lines. 

There  has  been  considerable  work  in  recent  years  on  the  commensurability  of  the  separations  of 
spectrum  lines,  that  is,  on  the  existence  of  a  fundamental  interval  of  which  the  separations  of  all  com- 
plex lines  are  multiples,  and  on  the  extent  to  which  this  applies  to  the  separations  of  triplets  in  which 

*  Numbers  in  parentheses  indicate  references  to  the  literature  on  p.  65. 


4  INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

there  is  always  a  great  diversity  for  the  lines  of  the  same  element.  As  this  point  will  receive  a  good  deal 
of  attention  in  the  consideration  of  the  results  for  the  spectra  of  iron  and  titanium,  it  may  be  well  to  go 
briefly  into  this  portion  of  the  theory. 

If  the  Zeeman  phenomenon  were  in  full  accord  with  the  simplest  form  of  the  electron  theory  as  given 
by  Lorentz,  all  lines  would  show  the  separation  of  the  "normal  triplet,"  in  which  the  distance  of  each 
side  component  from  the  central  line  would  be  given  by  the  relation 

e    HX2 
AX= 

m    4-irv 

where  e/m  is  the  ratio  of  charge  to  mass  of  the  electron,  H  the  field-strength,  and  v  the  velocity  of  light. 
This  is  derived  (*a)  from  the  fact  that  the  change  of  period  of  the  light  producing  one  side  com- 
ponent is  eH/2tn  in  2ir  seconds,  or  eH/4irm  vibrations  in  one  second.  The  number  of  vibrations  per 
second  is  n=v/\.  The  change  of  frequency  is  then 

,       vd\     eH 
dn=—==- 

X  47TWI 

from  which 

„      e     HX2 

AX= 

m    4irv 

If  v  be  expressed  in  centimeters  per  second,  the  change  in  frequency  per  cm  length  is 

AX  ^  e      H 
XJ      m    4« 

The  factor  e/m  is  here  expressed  in  electro-magnetic  units.  This  value  of  AX/X2  for  a  given  field  deter- 
mines the  separation  of  the  side  components  of  the  "normal  triplet"  from  the  central  line,  and  a  con- 
siderable number  of  lines  in  a  spectrum  will  usually  give  a  value  of  e/m  in  close  agreement  with  that 
obtained  for  cathode  rays.  The  separation  of  the  majority  of  triplets,  however,  differs  from  the  normal 
type,  though  sometimes  by  even  multiples.  This  means  either  that  there  are  real  differences  in  the  values 
of  e/m  for  different  negative  electrons,  or  that  the  relation  derived  from  the  elementary  theory  is  not 
sufficiently  general.  Lorentz  inclines  to  the  latter  view  (40).  In  discussing  this  question,  Voigt  (30) 
observes  that  it  is  by  no  means  certain  that  the  field  acting  upon  a  given  electron  is  the  same  as  that 
which  we  measure  by  one  of  our  regular  methods.  The  field  due  to  the  movement  of  charged  parts  of 
the  molecule  itself  must  be  recognized  as  possibly  superposed  on  the  external  field  due  to  the  magnet. 

The  elementary  theory  does  not  provide  for  the  more  complicated  types  of  separation,  nor  does  any 
extension  so  far  worked  out  cover  them  satisfactorily.  However,  an  examination  of  the  results  of  Runge 
and  Paschen  (18)  (24)  for  several  elements  and  of  Lohmann  (27)  for  the  spectrum  of  neon  (with  the 
echelon  spectroscope)  enabled  Runge  (»g)  to  enunciate  the  following: 

Die  bisher  beobachteten  komplizicrten  Zerlegungen  von  Spektrallinien  im  magnetischen  Felde  zeigen  die  folgende  Eigentiim- 
lichkeit:  Die  Abstande  der  Komponenten  von  der  Mitte  sind  Vielfache  eines  aliquoten  Teil  des  normalen  Abstiindes 

_AX^g     H 
X2     m  4^v 
Sicher  beobachtet  sind  bisher  die  Teile  a/2,  0/3,  0/4,  0/5,  a/6,  0/7,  a/n,  0/12. 

This  work  of  Runge  is  regarded  by  Voigt  as  showing  that  the  internal  field  acting  on  the  electron  can 
have  little  effect,  that  the  electrons  within  the  molecule  have  the  same  value  of  e/m  as  that  of  cathode  rays. 

Such  a  relation  between  the  separation  for  individual  lines  and  that  of  the  normal  triplet  is  of  high 
interest  when  applied  to  spectra  containing  many  lines.  It  has  been  examined  by  Moore  (28)  for  the  spectra 
of  barium,  yttrium,  zirconium,  osmium,  and  thorium,  and  relations  similar  to  those  observed  by  Runge 
have  been  obtained.  The  objection  can  be  raised  to  this  method  that,  by  choosing  small  fractions  of  the 
interval  a  and  correspondingly  large  multiples,  the  difference  between  the  calculated  and  observed  values 


THEORY  AND  FORMER  INVESTIGATIONS.  5 

can  be  made  as  small  as  we  please  and  brought  within  the  errors  of  measurement.  Runge  gives  a  cri- 
terion as  to  how  far  it  is  allowable  to  go  in  such  calculations.  This  question  of  commensurability  will 
receive  attention  in  the  following  study  of  the  iron  and  titanium  spectra. 

Dissymmetry  in  the  separation  and  in  the  intensity  of  components  on  the  red  and  violet  sides  has 
been  observed  many  times  in  Zeeman  investigations.  Voigt  (3*)  arrived  at  the  conclusion  that  light 
observed  at  right  angles  to  the  force-lines  should  give  a  triplet  whose  red  component  is  slightly  closer  to 
the  central  line  and  stronger  than  the  violet  component.  Observations  by  Zeeman  (30)  on  the  iron 
spectrum  gave  a  number  of  cases  where  such  a  dissymmetry  seemed  to  exist.  Reese  (12)  also  found  triplets 
and  lines  of  higher  separation  for  several  elements  which  appeared  to  show  the  effect.  More  recently 
a  series  of  papers  has  been  published  by  Zeeman  (31)  comparing  the  mercury  triplets  A  5770  and  \57gi 
by  various  optical  methods.  The  latter  line  is  distinctly  shown  to  have  its  red  component  nearer  the 
central  line  than  is  the  violet  component,  while  A  5770  remains  perfectly  symmetrical.  The  amount  of 
dissymmetry  appeared  to  vary  as  the  square  of  the  field-strength.  This  confirmed  a  measurement  made 
about  the  same  time  by  Gmelin  (32)  with  the  echelon  grating.  A  dissymmetry  of  this  sort  is  always  small 
and  difficult  of  detection.  Large  dissymmetries  are  to  be  classified  as  abnormal  separations.  A  few  lines 
of  such  a  character  occur  in  the  iron  and  titanium  spectra,  which  will  be  noted  later.  Lines  of  very  pro- 
nounced dissymmetry  were  measured  by  Jack  (33)  in  the  spectra  of  tungsten  and  molybdenum.  Chromium 
also  shows  a  great  number  of  unsymmetrical  separations.  Some  striking  cases  were  observed  by  Dufour  (34) , 
and  many  others  have  been  photographed  in  this  laboratory.  The  theory  of  coupled  electrons,  by  which 
Voigt  (35)  has  sought  to  explain  complex  separations  in  general,  allows  for  the  occurrence  of  such  dissym- 
metries. 

The  magnetic  separation  of  absorption  lines,  or  the  "inverse  Zeeman  effect,"  has  been  investigated 
by  a  number  of  observers,  as  a  rule  for  only  a  few  lines.  In  such  experiments  white  light  is  passed  through 
the  vapor  of  a  luminous  source  placed  between  the  poles  of  a  magnet.  It  was  shown  by  Konig  (36)  and 
Cotton  (37)  that  there  is  a  full  correspondence  between  the  effects  of  the  magnetic  field  for  both  emission 
and  absorption  lines.  The  splitting  of  lines  in  the  spectra  of  sun-spots  observed  by  Hale  (38)  was  thus 
proved  to  be  due  to  the  action  of  magnetism  by  comparing  the  Zeeman  effect  for  the  same  lines  as  pro- 
duced in  the  laboratory.  The  peculiarities  in  separations  of  sun-spot  lines  can  thus  be  studied,  as  is  being 
done  in  this  laboratory  and  by  Zeeman  and  Winawer  (39)  in  their  investigation  of  special  polarization 
effects  for  absorption  lines,  especially  when  the  light  passes  at  different  angles  to  the  magnetic  force-lines. 

2.  POSSIBLE  RELATION  BETWEEN  ZEEMAN  SEPARATION  AND  PRESSURE  DISPLACEMENT. 

A  preliminary  paper  on  this  subject  has  been  published  by  the  author  (40).  In  the  discussion  of  the 
present  results  material  will  be  offered  for  an  extended  study  to  test  the  hypothesis  of  a  direct  connection 
between  the  Zeeman  effect  and  the  pressure  displacement  for  spectrum  lines.  That  such  a  relation  exists 
has  been  strongly  advocated  by  Humphreys  (4« )  in  a  series  of  papers  which  have  been  summarized  (4»)  by 
him,  together  with  all  other  pressure  investigations  up  to  the  year  1908.  Humphreys's  hypothesis,  briefly 
stated,  is  that  the  part  of  the  atom  to  which  the  light  impulse  is  due  is  a  ring  of  electrons,  rotating  with 
a  period  of  the  order  of  the  light  vibration.  Each  of  the  electron  rings  will  then  set  up  a  magnetic  field 
of  its  own.  The  luminous  gas  will  be  in  a  condition  of  minimum  potential  energy  when  the  planes  of 
the  rings  are  parallel  and  the  electrons  revolving  in  the  same  direction.  We  must,  however,  in  view  of 
the  Zeeman  effect,  consider  that  different  rings  may  rotate  in  opposite  directions,  and  assume  merely 
that  the  regular  condition  is  a  rotation  of  the  electrons  in  orbits  approximately  circular,  with  a  tendency 
for  the  planes  of  these  to  become  parallel.  The  effect  of  pressure  in  the  surrounding  medium  will  be  to 
bring  the  rings  closer  together,  thereby  altering  their  mutual  induction.  If  two  rings  rotating  in  the  same 
direction  are  made  to  approach,  the  current  in  each  ring  will  decrease,  which  means  a  retardation  of  the 
rotating  electrons  and  an  increase  of  period  in  the  corresponding  light  vibration,  resulting  in  a  shift  of 
the  spectrum  lines  toward  the  red. 


6  INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

If  rings  of  opposite  rotation  are  forced  closer  together,  their  motion  will  be  accelerated,  resulting 
in  a  shift  of  the  spectrum  lines  to  the  violet.  Assuming  that  both  directions  of  rotation  are  present  for 
electrons  producing  each  spectrum  line,  the  general  result  will  be  a  widening  of  all  lines  as  the  pressure 
increases,  with  a  prevailing  shift  of  the  maximum  of  each  line  toward  the  red.  This  last  is  due  to  the 
fact  that  the  condensing  action  of  the  pressure  on  rings  rotating  in  the  same  direction  is  assisted  by  the 
effort  of  these  rings  to  get  into  the  strongest  part  of  their  mutual  field;  while  for  oppositely  rotating 
rings  the  approach  is  opposed  by  the  magnetic  action,  so  that  on  the  whole  the  retardation  of  the  period 
for  a  given  line  is  greater  than  the  acceleration,  and  the  line,  while  being  widened  toward  both  red  and 
violet,  has  its  maximum  intensity  moved  toward  the  red. 

Another  theory,  by  Richardson  (43),  opposes  the  connection  of  pressure  displacement  with  Zeeman 
effect.  Instead  of  basing  his  reasoning  on  magnetic  perturbations,  Richardson  considers  the  electron 
as  an  oscillator  which  sets  up  an  alternating  electrostatic  field  in  its  neighborhood.  This  field  would 
produce  forced  vibrations  in  the  electrons  belonging  to  neighboring  atoms,  an  effect  increased  by  pres- 
sure in  the  medium.  The  electric  field  produced  by  the  forced  vibrations  would  then  react  on  that  of 
the  radiating  electrons.  The  mathematical  development  gives  a  change  of  wave-length  proportional  to 
the  pressure  and  toward  the  red.  Worked  out  numerically  with  the  available  data,  the  electrostatic 
resonance  theory  requires  values  for  the  pressure  displacement  many  times  greater  than  those  observed 
experimentally.  A  modified  conception  of  the  equilibrium  conditions  might  account  for  this  discrepancy. 

Richardson  objects  to  Humphreys's  theory  largely  on  the  ground  that  the  magnetic  disturbances 
of  period  would  be  far  too  small  to  account  for  the  observed  displacements  of  lines  unless  the  magnetic 
field  for  any  atom  is  greater  than  that  corresponding  to  saturated  iron,  which  Richardson  holds  to  be 
an  upper  limit.  This  is  replied  to  by  Humphreys  in  a  later  paper  (41*,  in  which  he  questions  the  right  to 
base  the  possible  magnetic  intensity  of  iron  atoms  upon  the  properties  of  iron  in  large  masses,  since  the 
permeability  and  saturation  point  depend  upon  many  factors  of  composition  and  physical  condition. 
Going  farther,  Humphreys  considers  an  ideal  electron  ring  and  deduces  an  expression  for  the  change  of 
rotation  frequency  brought  about  by  an  external  magnetic  field  H,  such  as  that  due  to  a  neighboring 
electron  ring.  This  is  found  to  give  an  expression  for  the  change  of  wave-length  AX  in  the  ether  vibra- 
tions of  original  wave-length  X  which  reduces  to  AX/HX2=C,  a  constant,  which  is  Preston's  law  for  the 
Zeeman  phenomenon,  indicating  that  the  ideal  electron  ring  is  very  similar  in  structure  to  the  actual 
radiating  particle.  If  this  similarity  be  admitted,  Humphreys  is  justified  in  his  next  step,  which  is  the 
substitution  of  known  values  in  the  expression  for  the  change  of  wave-length  of  ether  vibrations  pro- 
duced by  a  change  in  the  period  of  the  electron  ring.  This  gives  a  field-intensity  for  the  rotating  ring 
of  45  X  io7,  which  is  about  ten  thousand  times  that  of  the  strongest  fields  used  in  spectroscopic  work. 
The  change  in  mutual  induction  by  pressing  together  electron  rings  having  fields  of  this  magnitude  may 
be  expected  to  give  shifts  of  spectrum  lines  of  the  order  of  those  measured. 

A  third  theory  is  that  presented  by  Larmor  (44),  who  treats  the  electron  as  a  Hertzian  doublet  in  a  field 
of  electric  force.  This  field  would  be  altered  by  any  change  in  the  distribution  of  material  particles  in 
the  medium  such  as  would  result  from  increased  pressure.  A  molecule  approaching  a  vibrating  electron 
would  decrease  the  rigidity  of  the  ether  at  that  point.  A  lowering  of  the  ether  strain  would  tend  to  increase 
the  period  of  the  electron,  and  it  is  shown  that  this  might  give  displacements  of  the  magnitude  observed 
for  spectrum  lines.  A  note  by  Humphreys  (4'c)  points  out  that  several  consequences  of  Larmor's  theory 
agree  only  to  a  limited  degree  with  observed  facts,  although  his  claim  that  Larmor's  equations  should 
give  the  amount  of  displacement  inversely  proportional  to  the  wave-length  is  incorrect. 

The  interacting  magnetic  atoms  of  Humphreys  seem  to  provide  a  very  plausible  theory,  but  experi- 
mental data  have  been  lacking  to  show  the  probability  of  a  connection  between  the  effects  of  pressure 
and  magnetic  field  on  spectrum  lines.  Humphreys  considers  that,  in  general,  lines  of  large  Zeeman 
separation  are  strongly  displaced  by  pressure,  but  admits  that  there  is  scanty  material  on  which  to 


THEORY  AND  FORMER  INVESTIGATIONS.  7 

base  this  conclusion.  The  refusal  of  banded  spectra,  notably  that  of  carbon,  to  show  either  Zeeman  effect 
or  displacement  has  often  been  cited  as  probably  resulting  from  a  connection  between  the  two  phenom- 
ena, and  interesting  developments  on  this  point  have  recently  been  presented.  Dufour  (45)  obtained 
Zeeman  separations  for  the  component  lines  of  the  band  spectra  of  the  chlorides  and  fluorides  of  the 
alkaline  earths,  the  magnitude  of  separation  being  about  the  same  as  for  line  spectra.  A  short  time 
after,  Rossi  (46)  selected  three  of  these,  the  fluorides  of  calcium,  strontium,  and  barium,  and  obtained 
distinct  pressure  shifts  for  the  bands,  the  shift  being  of  the  same  order  as  for  line  spectra.  Comparing 
his  results  with  those  of  Dufour,  Rossi  did  not  find  any  general  relation  between  the  magnitude  of 
the  two  effects.  Numerous  investigations  on  the  Zeeman  effect  for  banded  spectra  have  been  made 
during  the  past  two  years,  part  of  which  are  summarized  by  Dufour  (47),  but  corresponding  results 
for  pressure  have  not  been  obtained. 

A  detailed  comparison  of  Zeeman  separation  and  pressure  displacement  for  the  line  spectra  of  iron 
and  titanium  will  be  made  in  the  present  paper. 

3.  FORMER  INVESTIGATIONS  OF  THE  ZEEMAN  EFFECT  FOR  IRON. 

Passing  to  special  investigations  on  the  iron  spectrum  in  which  the  magnetic  separations  for  certain 
lines  have  been  described  and  measured,  the  first  to  be  mentioned  is  that  of  Becquerel  and  Deslandres  (9). 
In  this,  10  lines  are  given  from  \^&2i  to  X3&73,  most  of  them  of  complex  separation.  Shortly  after, 
these  writers  used  a  stronger  field  and  covered  a  larger  region.  This  publication  (10)  gives  no  measure- 
ments, being  confined  to  a  description  of  a  few  interesting  types  of  lines. 

A  note  by  Ames,  Earhart,  and  Reese  (")  speaks  of  the  general  characteristics  of  the  iron  lines  between 
\35oo  and  X  4400,  with  special  mention  of  the  type  of  separation  for  a  few  lines.  Reese  (n)  gives  measure- 
ments of  the  separation  for  23  of  the  stronger  lines  in  this  region,  the  source  being  a  carbon  spark  with 
iron  as  an  impurity.  Kent  (13)  continued  the  investigation  with  better  equipment,  measuring  about  90 
iron  lines  between  X  3550  and  X  4550.  Special  attention  was  paid  to  a  number  of  complex  lines.  Reese 
had  observed  that  the  lines  on  his  plates  could  be  classified  as  to  amount  of  separation  in  about  the  same 
way  that  they  were  classified  as  to  pressure  displacement.  Kent,  with  more  material  available  for  com- 
parison, found  that  this  relation  was  not  verified. 

The  paper  by  Zeeman  (30)  was  concerned  chiefly  with  the  question  of  a  dissymmetry  of  the  side  compo- 
nents of  triplets,  as  measured  from  the  central  line.  Hartmann  (48)  investigated  the  structure  of  a  num- 
ber of  iron  lines  with  the  echelon  spectroscope.  He  did  not,  however,  obtain  as  good  resolution  of  com- 
plex types  as  was  given  by  the  grating  method  in  the  present  investigation.  The  most  extensive  set  of 
measurements  thus  far  published  on  the  iron  spectrum  is  given  in  the  thesis  of  Mrs.  van  Bilderbeek  (49) . 
These  are  from  photographs  made  with  a  concave  grating  for  a  magnetic  field  of  32,040  gausses.  Measure- 
ments are  given  for  137  lines  between  X 2382  andX452g.  Of  these  lines  55  (40  per  cent)  are  to  the  violet 
of  the  region  covered  by  my  photographs;  the  others  are  the  stronger  lines  among  those  given  in  my 
tables,  and  have  been  of  great  service  in  determining  the  field-strength.  As  will  be  noted  later,  there  is 
an  excellent  agreement  between  the  two  sets  of  measures  for  all  lines  whose  components  are  sharp  enough 
to  give  measurements  of  high  weight.  Besides  checking  my  standard  field,  the  agreement  between  Mrs. 
van  Bilderbeek's  field-value  and  that  which  I  had  obtained  by  other  methods  supports  the  contention 
in  her  paper  that  the  field-strengths  published  by  Kent  and  by  Hartmann  are  both  low. 

It  will  thus  be  seen  that  several  investigations  of  special  regions  have  been  carried  out  for  the  iron 
spectrum  with  regard  to  the  Zeeman  effect.  The  region  covered,  however,  has  not  extended  beyond 
about  X  4500,  with  the  exception  of  a  few  lines  in  the  green  examined  by  Hartmann,  leaving  nearly  three- 
fourths  of  the  range  included  in  this  paper  as  new  territory.  For  the  region  from  X37oo  to  X45oo,  which 
has  been  covered  to  some  extent  by  others,  the  previous  investigators  have  measured  only  the  stronger 
lines,  the  description  of  the  character  of  separation  is  usually  brief  or  lacking,  and  the  complex  separa- 


8  INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

tions  are  but  incompletely  considered.  The  range  of  spectrum  covered  previously  has  not  been  sufficient 
to  draw  any  conclusions  regarding  the  variation  of  separation  with  wave-length,  the  comparison  with 
pressure  effects  and  other  changes  of  physical  condition  has  not  been  carried  out,  and  no  application 
has  been  made  of  Runge's  rule  for  the  commensurability  of  the  distances  between  components.  These 
points  will  be  handled  in  the  present  paper  as  fully  as  the  material  will  permit.* 

4.  FORMER  INVESTIGATIONS  OF  THE  ZEEMAN  EFFECT  FOR  TITANIUM. 

A  set  of  measurements  was  published  by  Purvis  (50)  for  many  of  the  stronger  lines  of  titanium  from 
\28oo  to  XSOQO.  The  majority  of  these  are  in  the  ultra-violet,  86  lines  being  measured  in  the  region 
covered  by  my  tables.  Three  violet  triplets  were  measured  by  Reese  («).  A  former  paper  by  the  author(s') 
gave  descriptions  and  measurements  for  291  lines  between  \39oo  and  X66oo.  These  were  made  from 
the  first  set  of  plates  taken  in  this  laboratory,  the  first  and  second  orders  of  the  i3-foot  (4  m)  spectro- 
graph  being  used,  with  a  field  of  12,500  gausses.  The  data  for  the  present  paper  were  compiled  from  a 
much  more  extensive  set  of  plates,  taken  with  higher  dispersion  and  stronger  field,  the  gain  in  all  points 
being  so  great  that  these  measures  may  be  taken  as  superseding  the  previous  ones.  A  still  earlier  paper 
by  the  author  ( s»)  gave  preliminary  measures  of  some  titanium  and  iron  lines  in  a  discussion  of  the  charac- 
ter of  their  separation  in  the  laboratory  as  compared  to  that  observed  in  sun-spot  spectra. 


*  Note  added  January,  1912:  A  dissertation  by  Immina  Maria  Graftdijk  on  Magnelische  Splilsing  van  ket  Nikkei-  en  Kobalt- 
Spectrum  en  van  het  Ijzer-Speclrum  (Amsterdam,  1911)  has  just  been  received.  Measurements  are  given  for  38  of  the  stronger  iron 
lines  between  A  4300  and  /".  6500  for  a  field  of  32,040  gausses.  The  measured  separations  of  triplet  lines  agree  in  general  very  closely 
with  those  presented  in  this  paper.  The  only  notable  discrepancies  are  for  a  few  complex  lines  where  a  large  difference  in  field 
necessarily  alters  the  appearance  of  the  components  which  are  measured. 


APPARATUS  AND  METHODS, 
i.  SPARK  APPARATUS. 

The  source  of  light  used  in  all  of  the  work  was  a  spark  discharge  from  a  5-kw  transformer  made 
according  to  special  design  by  the  Peerless  Electric  Company,  of  Warren,  Ohio.  The  coils  of  this  trans- 
former are  immersed  in  the  best  moisture-free  oil  and  contained  in  a  cylindrical  iron  tank  83  cm  in  diameter 
and  125  cm  high.  The  primary  and  secondary  leads  are  passed  through  the  flat  top  of  the  transformer, 
on  which  is  a  large  knife  switch  for  the  regulation  of  the  secondary  voltage.  The  bar  of  this  switch  forms 
the  radius  of  a  circle,  one  end  being  pivoted,  while  the  other  end  fits  into  any  one  of  a  series  of  jaws  along 
the  circumference  of  the  circle.  The  connections  with  the  transformer  coils  are  such  that  the  secondary 
voltage  may  be  10,  20,  40,  80,  160,  320,  or  640  times  the  impressed  primary  voltage,  according  to  which 
jaw  the  bar  of  the  switch  is  fitted  into.  Thus  with  100  volts  on  the  primary  the  secondary  voltage  is 
1,000,  2,000,  4,000,  8,000,  16,000,  32,000,  or  64,000,  according  to  the  connection.  The  use  of  a  rheostat 
in  the  primary  circuit  to  regulate  the  impressed  voltage  will  obviously  give  any  secondary  potential 
desired  up  to  64,000  volts.  The  adjustable  rheostat  used  is  one  capable  of  carrying  heavy  currents  con- 
tinuously. It  is  composed  of  sheets  of  tin  cut  into  strips  i  cm  wide  by  cutting  almost  across  the  sheet 
first  from  one  side  and  then  from  the  other.  The  sheets  of  strips  thus  made  are  mounted  vertically  against 
strips  of  asbestos  fastened  to  a  wooden  frame,  the  distance  between  successive  sheets  being  sufficient 
to  provide  air  circulation  for  cooling.  Copper  wires  soldered  to  the  tin  strips  at  the  proper  intervals 
lead  to  knife  switches  on  the  top  of  the  rheostat  frame.  Various  combinations  of  these  switches  place 
parts  of  the  tin  resistance  in  series  or  parallel,  and  permit  the  resistance  to  be  reduced  by  short  steps 
until  all  is  out.  One  switch  may  be  connected  to  an  external  resistance,  thus  allowing  the  latter  to  be 
connected  in  series  with  any  part  of  the  tin  resistance  for  fine  adjustment  of  the  rheostat.  A  bank  of 
twenty-four  32-cp  incandescent  lamps  in  parallel  is  usually  used  in  this  branch. 

The  primary  current  is  supplied  at  about  104  volts  from  one  side  of  the  three-phase  connection  of  a 
1 5-kw  transformer.  This  transformer  and  one  similar  to  it  are  mounted  in  the  transformer  room  of  the 
laboratory,  fed  by  2200  volts  from  the  lines  of  the  Southern  California  Edison  Company,  and  are  used 
together  to  supply  the  2o8-volt  three-phase  current  for  the  D.C.  motor-generator  set  which  furnishes 
current  to  the  electro-magnet. 

Two  glass-plate  condensers  were  used  for  the  spark  circuit  during  the  series  of  experiments.  The 
more  efficient  one,  used  in  taking  the  later  photographs,  is  built  up  of  16  sheets  of  plate  glass,  of  area 
61  X  66  cm,  and  thickness  5.5  to  6.0  mm,  laid  horizontally  in  a  strong,  copper-lined  wooden  tank. 
Between  the  glass  plates  and  at  the  top  and  bottom  of  the  pile  are  sheets  of  copper,  17  in  number,  each 
0.9  mm  in  thickness  and  with  an  area  of  3330  sq  cm,  one  side  of  each  sheet  having  a  tongue  2.5  cm  long 
projecting  beyond  the  glass  plates  for  the  connection,  while  the  plates  immediately  above  and  below  are 
cut  away  so  as  not  to  reduce  the  insulation  at  this  point.  Around  the  other  three  sides  the  copper  is 
cut  so  as  to  come  2.5  cm  inside  the  edge  of  the  glass  plates.  This  arrangement,  together  with  the  form 
in  which  the  copper  is  cut  on  the  fourth  side  where  the  tongues  project,  insures  a  distance  of  5.7  cm 
along  the  glass  from  the  edge  of  one  copper  plate  to  the  edge  of  the  next.  The  condenser  plates  are  sepa- 
rated from  the  copper  lining  of  the  tank  by  a  wood  flooring  2.5  cm  thick  and  held  in  place  by  a  wooden 
box  inside  the  tank.  A  thick  copper  wire  is  soldered  to  each  of  the  tongues  coming  from  the  copper  plates 
and  the  other  end  of  the  wire  connected  to  a  binding  post  set  in  a  plate  of  fiber  extending  across  the  width 
of  the  tank,  7.5  cm  below  the  top.  This  fiber  plate  was  at  first  placed  level  with  the  top,  as  shown  in  the 
photograph  of  the  laboratory  (Plate  I).  This  condenser  is  entirely  immersed  in  the  best  transformer  oil, 
which  fills  the  tank  up  to  about  5  mm  above  the  fiber  plate,  thus  insulating  the  condenser  plates  and  also 

9 


10 


INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 


the  binding  posts,  the  screw  tops  of  the  latter  projecting  from  the  oil  to  receive  the  wires  connecting  them 
in  any  desired  combination  to  the  discharge  circuit,  so  that  the  whole  or  any  part  of  the  condenser  may 
be  used.  An  adjustable  spark-gap  between  the  nearer  binding  posts  on  each  side  protects  the  condenser 
against  too  long  a  spark  in  the  circuit  which  might  cause  the  glass  to  be  punctured.  Connecting  wires 
from  the  two  central  binding  posts  are  inclosed  in  thick  glass  tubes  which  pass  through  a  second  fiber 
plate  directly  above  the  first  and  level  with  the  top  of  the  tank  to  the  high  tension  wires  supported  by 
glass  insulators  and  extending  across  the  laboratory  below  the  ceiling.  A  wooden  cover  fits  into  the  top 
of  the  tank  and  protects  all  parts  of  the  condenser  from  dust.  The  leads  from  the  transformer  pass  to 
the  overhead  wires  and  other  leads  drop  down  to  any  piece  of  apparatus  under  the  wires,  so  that  the 
heavy  condenser  can  remain  permanently  in  its  place. 

In  addition  to  the  condenser,  the  circuit  from  the  transformer  contains  a  self-induction  spool  and 
spark  gap  in  series  with  the  spark  under  observation.  Several  self-induction  coils  are  available,  but  the 
one  regularly  used  consists  of  207  turns  of  insulated  copper 
wire  wound  on  a  wooden  cylinder  132  cm  long  and  13  cm 
in  diameter.  A  sliding  contact  may  be  moved  to  any  point 
along  the  spool  so  as  to  include  any  desired  portion  of  the 
self-induction. 

The  terminals  for  the  spark  on  which  the  magnetic 
field  acts  require  different  handling  according  as  the  sub- 
stance under  examination  is  magnetic  or  not.  In  the 
experiments  with  titanium,  small  pieces  of  the  substance 
known  as  "cast  titanium,"  obtained  from  Eimer  and 
Amend  of  New  York,  were  held  in  small  brass  clamps,  the 
vertical  rods  of  which  passed  through  larger  horizontal 
brass  pieces  set  in  a  thick  piece  of  fiber,  through  the 
middle  of  which  a  brass  rod  passed  and  fitted  into  a 
clamp,  movable  up  and  down  on  a  support  attached  to 
the  base  of  the  electro-magnet. 

When  iron  terminals  were  used  it  was  necessary  that 
they  be  held  rigidly  in  place  on  account  of  the  attraction 
of  the  magnet.  In  all  cases  small  cylinders  of  Norway 
iron  were  screwed  on  the  end  of  brass  rods.  The  size  of 
the  iron  tips  varied  somewhat  according  to  the  kind  of 
spark  desired  and  the  width  of  the  magnetic  gap  used. 
Those  most  generally  used  with  a  strong  field  were  3.5  mm  in  diameter  and  about  10  mm  long.  In  the 
earlier  work  the  iron-tipped  brass  rods  were  held  in  a  hard-wood  frame  composed  of  two  vertical  rings 
held  apart  by  four  horizontal  pieces.  The  wooden  rings  fitted  over  the  magnet  core,  against  the  face  of 
each  coil,  while  the  brass  rods  passed  with  some  friction  through  two  of  the  horizontal  wood  pieces  at 
opposite  ends  of  the  diameter  of  the  rings.  A  better  holder  for  iron  terminals  was  devised  later.  This  is 
shown  in  Fig.  i  and  is  a  modification  of  that  used  for  non-magnetic  substances,  the  parts  being  much 
more  rigid.  The  rod  of  6  mm  diameter  to  which  the  iron  tip  is  screwed  passes  through  a  square  brass 
rod  16  mm  in  thickness,  having  a  saw-cut  from  the  hole  out  to  the  end.  A  screw  at  right  angles  to  this 
saw-cut,  worked  with  a  bar,  serves  to  clamp  the  rod  so  firmly  that  the  magnet  does  not  move  it.  As 
the  column  supporting  the  holder  is  screwed  to  the  base  of  the  magnet,  all  parts  could  be  clamped  so 
firmly  that  the  iron  tips  were  held  exactly  in  place. 

The  spark  length  for  both  iron  and  titanium  was  usually  short  on  account  of  the  proximity  of  the 
magnet  poles  and  the  tendency  of  the  spark  to  jump  to  these.    With  iron  terminals,  particles  were  given 


APPARATUS  AND  METHODS.  I  I 

off  rapidly  by  the  strong  transformer  discharge  and  it  was  necessary  to  clean  these  off  every  few  minutes 
and  also  to  file  off  the  oxide  from  the  iron  tip.  Titanium  terminals  wore  away  rapidly,  owing  to  disin- 
tegration of  the  metal,  and  the  oxide  also  needed  to  be  removed  frequently  if  the  brightest  discharge  was 
to  be  obtained.  The  short  spark  gap  necessitated  an  auxiliary  gap  in  series,  as  otherwise  the  discharge 
was  not  sufficiently  disruptive  to  avoid  melting  the  terminals.  This  auxiliary  gap  was  a  simple  affair 
of  brass  mounted  on  fiber. 

When  using  the  spark,  the  various  parts  of  the  secondary  circuit,  as  well  as  the  step-up  connection 
and  the  current  in  the  primary,  were  adjusted  to  give  the  sort  of  spark  desired.  In  this  investigation 
self-induction  has  been  used  in  the  spark  circuit  somewhat  sparingly,  since  on  the  majority  of  the  photo- 
graphs it  was  necessary  to  obtain  the  fainter  lines  of  sufficient  strength  for  accurate  measurement.  Self- 
induction  in  the  spark  circuit  sharpens  the  Zeeman  components  in  about  the  same  degree  that  it  sharpens 
the  lines  of  the  regular  spark  spectrum,  but  the  brightness  of  the  spark  is  greatly  diminished  at  the  same 
time,  an  effect  only  partially  due  to  the  decrease  in  intensity  of  the  enhanced  lines.  The  weaker  lines  as 
a  whole,  especially  the  faint  and  diffuse  lines  of  iron,  are  so  reduced  by  self-induction  that  very  long 
exposures  are  required  to  bring  them  out.  A  compromise  must  be  made,  since  in  exposures  running 
many  hours,  especially  for  more  than  one  day,  there  is  risk  of  instrumental  disturbances.  The  method 
followed  was  to  use  the  spark  with  rather  high  self-induction  for  one  or  more  photographs  of  any  region 
containing  strong  lines,  and  especially  enhanced  lines,  for  which  moderate  exposure  time  was  sufficient, 
then  to  use  small  self-induction  for  photographs  in  which  as  many  of  the  weak  lines  as  possible  were 
desired.  The  loss  of  sharpness  in  such  cases  was  counteracted  as  far  as  possible  by  the  use  of  a  narrow 
slit  and  by  selecting  the  kind  of  plate  and  developer  which  would  give  the  sharpest  definition  and  at  the 
same  time  show  the  lines. 

2.  THE  ELECTRO-MAGNET. 

This  apparatus  is  of  the  Du  Bois  half-ring  type,  made  by  Hartmann  and  Braun  of  Frankfort.  It  is 
shown  (in  its  present  state,  after  being  rewound)  in  the  photograph  of  the  laboratory  (Plate  I).  The 
coils,  as  used  until  recently,  were  each  wound  with  1250  turns  of  No.  9  wire  (diameter  =3.0  mm).  They 
are  clamped  to  a  horizontal  iron  base  which  completes  the  magnetic  circuit.  The  magnetic  gap  is  varied 
by  moving  the  coils  upon  this  base,  which  is  itself  supported  by  three  legs  on  an  iron  plate.  A  hole  in 
the  center  of  this  plate  fits  over  a  pivot  in  the  middle  of  a  round  iron  table,  the  ends  of  the  plate  resting 
on  a  planed  ring  which  forms  the  rim  of  the  table.  The  magnet  can  thus  be  turned  in  any  desired  direc- 
tion by  rotating  the  base-plate  upon  the  planed  ring  of  the  table.  The  magnet  rests  upon  a  cement  pier 
60  cm  square  and  82  cm  high.  The  core  of  each  magnet  coil  is  pierced  by  a  horizontal  hole  17.5  mm  in 
diameter  for  the  transmission  of  light  along  the  lines  of  magnetic  force.  These  holes  are  filled  with  cylin- 
drical iron  rods  when  such  an  axial  opening  is  not  needed. 

A  variety  of  pole-pieces  was  used  for  the  magnet  according  to  the  way  in  which  the  spark  terminals 
were  arranged  and  the  directions  in  which  the  light  was  to  be  taken.  Into  each  vertical  face  of  the  magnet 
core  is  screwed  the  first  section  of  the  pole-piece,  a  truncated  cone  of  soft  iron  16.5  mm  thick,  whose 
double  angle  is  1 1 2°.  The  small  end  of  this  cone  is  a  circular  plane  surface  39  mm  in  diameter.  To  this 
circular  face  was  fastened  a  pole  tip  of  one  of  the  following  forms,  each  of  which  has  a  double  angle  equal 
to  that  of  the  truncated  cone  just  described. 

(a)  For  the  observation  of  the  light  from  the  iron  spark  parallel  to  the  lines  of  force,  the  magnet 
poles  themselves  were  used  as  spark  terminals  in  some  of  the  earlier  experiments.  In  this  arrangement 
the  faces  of  the  tips  were  circular,  of  6  mm  diameter.  One  pole  was  left  solid  and  the  other  pierced  with 
a  hole  3  mm  in  diameter,  the  spark  being  viewed  through  the  tubular  hole  in  the  core.  The  pole-tips 
were  each  insulated  from  the  core  by  mica  plates  and  held  in  place  by  fiber  screws.  The  method  gave 
trouble,  not  only  from  the  occasional  breaking  down  of  the  insulation,  but  from  the  fact  that  the  spark 
did  not  stay  in  front  of  the  hole  in  the  pole-piece.  It  had  the  advantage,  however,  that  the  field  was  not 
affected  by  the  introduction  of  extra  iron  as  spark  terminals. 


I  2  INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

(6)  A  stronger  light  from  the  spark  was  obtained  for  observation  along  the  axis  by  not  insulating  the 
pole-tips,  using  one  solid  and  the  other  pierced  as  in  (a),  with  the  spark  between  iron  tips  at  the  ends 
of  brass  rods  held  vertically  between  the  magnet  poles  by  means  of  a  wooden  frame  or  the  brass  and  fiber 
holder  described  on  p.  10.  Titanium  terminals  were  held  in  the  simple  clamp  described  above.  This 
worked  well  for  getting  the  "longitudinal  effect"  (w-component)  without  the  introduction  of  a  Nicol 
prism  in  the  optical  system.  Such  an  end-on  arrangement  is  of  course  necessary  for  the  study  of  the 
circular  polarization  of  Zeeman  components.  However,  for  general  work  in  measuring  the  separation 
of  components,  this  method  has  the  disadvantage  that  there  is  a  considerable  increase  of  field-intensity 
close  to  the  magnet  poles,  amounting  with  some  gaps  to  25  per  cent,  as  well  as  an  inequality  at  the  two 
poles  resulting  from  one  of  them  being  pierced,  so  that  the  sharpness  of  the  Zeeman  components  is  not 
all  that  could  be  wished. 

(c)  The  most  useful  method,  and  that  used  (with  varying  shapes  of  the  pole-tips)  for  almost  all  of 
the  best  observations,  was  to  set  the  magnet  at  right  angles  to  the  direction  at  which  the  light  was 
observed,  use  both  pole-pieces  solid,  and  separate  the  light  by  means  of  a  Nicol  prism  over  the  slit  into  that 
vibrating  in  a  plane  at  right  angles  to  the  magnetic  force-lines,  or  parallel  to  these.  This  arrangement 
made  it  possible  to  photograph  successively  the  Zeeman  components  given  respectively  by  vibrations 
perpendicular  and  parallel  to  the  force-lines  by  turning  the  Nicol  prism  through  90°,  leaving  the  magnet 
unchanged.  Furthermore,  by  projecting  the  image  so  that  only  the  h'ght  from  that  part  of  the  spark 
midway  between  the  magnet  pole-pieces  falls  upon  the  slit  of  the  spectrograph,  the  FIQ 

change  of  field  near  the  pole-pieces  does  not  disturb  the  definition  of  the  Zeeman  com- 
ponents. Even  if  the  slit  is  long  enough  so  that  parts  of  the  image  come  from  regions 
of  different  field-strength,  the  spectrograph,  not  being  astigmatic,  shows  merely  a 
wider  separation  toward  the  ends  of  the  components,  the  sharpness  not  being  affected, 
so'  that  accurate  measurements  may  be  made  by  selecting  the  narrowest  portion  of  the 
separation. 

Three  forms  of  magnet  pole-tips  were  used  with  this  arrangement.  In  the  first, 
the  conical  tips  ended  in  circular  faces  6  mm  in  diameter.  This  was  used  for  most  of 
the  work  on  iron  and  for  the  earlier  work  on  titanium.  With  titanium,  however,  the 
pieces  of  metal  were  irregular  in  shape  and  often  rather  large,  so  that  with  a  short 
magnetic  gap  it  was  difficult  to  bring  the  terminals  close  enough  together  to  avoid  sparking  to  the 
magnet  pole-pieces.  The  later  and  best  set  of  titanium  plates  was  taken  with  pole-pieces  somewhat 
chisel-shaped,  made  by  milling  out  opposite  sides  of  a  conical  tip  of  12  mm  face  to  a  thickness  of  1.5  mm. 
The  thin  ends  were  then  placed  parallel  to  each  other  and  in  a  line  with  the  beam  of  light  passing  to  the 
slit.  This  gave  a  very  uniform  field  for  the  light  of  the  thick  spark,  part  of  the  vapor  of  which  might 
otherwise  have  gotten  into  weak  portions  of  the  field.  Probably  the  best  design  is  a  modification  of  that 
just  described,  in  which  the  chisel  edge  was  left  3  mm  in  thickness  and  12  mm  long,  and  not  so  deeply 
milled  as  before.  This  form  of  tip  gave  a  very  strong  field  and  a  gap  of  6  mm  could  be  used  without  diffi- 
culty. The  drawing  in  Fig.  2  shows  this  design,  with  which  a  number  of  the  later  iron  spectra  were  taken. 

A  current  of  10  to  12  amperes  from  a  1 2. s-kw  generator  was  generally  used  for  the  magnet  circuit. 
15  amperes  could  be  used  for  runs  of  two  or  three  hours,  but  the  magnet  rapidly  became  heated.  This 
current  was  almost  sufficient  to  saturate  the  core  and  a  larger  current  gave  but  a  small  increase  of  field. 
The  heating  of  the  core  by  long-continued  runs,  even  at  10  amperes,  was  considerable  in  warm  weather, 
when  the  two  electric  fans  used  to  blow  the  sparks,  and  which  also  played  on  the  magnet,  exerted  little 
cooling  effect.  Almost  at  the  close  of  this  investigation  a  very  efficient  means  of  cooling  the  core  was 
devised.  Injuries  to  the  insulation  of  the  wire  made  it  necessary  to  rewind  both  magnet  coils.  When 
the  cores  were  laid  bare,  a  spiral  of  soft  copper  tubing  of  6  mm  outside  diameter  and  4  mm  bore  was 
wound  around  each  core  next  to  the  iron.  Strips  of  "sooo-volt  linen"  were  wound  over  the  spiral  as 


APPARATUS  AND  METHODS. 


insulating  material,  the  face-plates  at  the  ends  of  the  coil  being  protected  by  ebonite  sheets,  and  1300 
turns  of  wire  were  wound  on  each  coil,  the  extra  100  turns  on  the  two  coils  more  than  compensating  for 
the  magnetic  leakage  caused  by  introducing  the  copper  spiral. 
With  a  stream  of  water  flowing  through  the  spiral,  the  core  remains 
perfectly  cool  and  a  current  of  14  amperes  may  be  used  without 
serious  heating  of  the  wire.  This  improvement  has  given  an 
increase  of  field  of  about  25  per  cent  over  what  could  previously 
be  used  for  long  runs  with  the  same  magnetic  gap. 

The  current  is  controlled  by  means  of  two  Ruhstrat  sliding 
resistances  in  parallel  and  is  read  to  o.i  ampere  by  a  Weston 
millivoltmeter  with  shunt  used  as  an  ammeter. 


3.  THE  SPECTROGRAPH. 

The  spectrograph  which  was  used  in  this  investigation  was 
described  briefly  in  the  general  account  of  the  Pasadena  labora- 
tory published  in  1908  (53).  It  is  of  the  Littrow  or  autocollimating 
type,  placed  vertically  in  a  well  30  feet  (9.1  m)  deep.  The  design 
of  this  spectrograph  was  worked  out  during  the  early  solar  inves- 
tigations on  Mount  Wilson  and  the  first  instrument  in  the  obser- 
vatory equipment  was  made  by  Wilh'am  Gaertner  of  Chicago,  and 
has  been  in  use  for  over  three  years  as  a  part  of  the  6o-foot  tower 
telescope  on  Mount  Wilson.  A  description  was  published  in 
Contributions  from  the  Mount  Wilson  Solar  Observatory  (54) .  When 
the  physical  laboratory  in  Pasadena  was  equipped  in  1908,  an 
exact  duplicate  of  the  mountain  spectrograph  was  obtained  from 
Gaertner,  with  the  addition  of  holders  for  lens  and  plane  grating 
to  give  a  focal  length  of  13  feet  (4  m)  when  desired,  as  well  as 
the  full  focal  length  of  30  feet  (9.1  m). 

The  details  of  the  mounting  of  the  spectrograph  can  be  seen 
from  the  drawing  in  Fig.  3  and  from  the  photograph  of  the  upper 
end  (Plate  II).  The  well  is  made  water-proof  with  a  h'ning  of 
brick,  several  layers  of  tarred  building  paper,  and  cement  plaster, 
the  dimensions  being  30  feet  (9.1  m)  below  the  floor  of  the  labora- 
tory and  8.5  feet  (2.6  m)  in  diameter.  Since  the  well  was  thor- 
oughly dried  out,  no  moisture  has  appeared  to  come  through  the 
walls.  The  cover  of  the  well  is  of  reinforced  concrete,  with  two 
openings.  A  circular  opening  at  the  east  side  is  inclosed  by  a 
cement  ring  70  cm  high  and  no  cm  outside  diameter,  which 
supports  the  metal  top  of  the  spectrograph.  Entrance  to  the 
well  is  provided  for  by  an  opening  at  the  south  side  closed  by  a 
wooden  cover,  from  which  a  vertical  iron  ladder  leads  to  the 
bottom.  Attached  to  the  iron  ladder  is  a  stout  wood  platform,  at 
such  height  that  the  parts  of  the  spectrograph  for  the  13  feet 
(4  m)  focus  can  be  conveniently  adjusted. 

The  spectrograph  consists  essentially  of  a  skeleton  steel  frame 
50  cm  square,  at  the  top  of  which  is  a  circular  cast-iron  plate  on  which  is  the  slit  and  holder  for  the 
photographic  plate,  while  below,  the  objectives  and  gratings  are  supported  in  the  steel  frame  at  the 


14          INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

proper  levels  for  the  focal  lengths  desired.  The  weight  of  the  frame  is  supported  by  a  concrete  pier 
placed  at  the  bottom  of  the  well.  This  pier  carries  an  iron  plate  with  a  spherical  cavity,  into  which 
fits  a  lubricated  hemisphere  on  the  lower  end  of  the  spectrograph  frame.  The  iron  plate  at  the  upper 
end  of  the  instrument  fits  loosely  inside  a  circular  iron  casting  imbedded  in  the  concrete  ring  already 
described.  The  whole  spectrograph  turns  easily  about  a  vertical  axis  by  means  of  a  gear  and  pinion  in 
the  outer  casting.  A  simple  clamping  device  holds  the  instrument  against  accidental  turning  when  in  use. 

The  slit  of  the  spectrograph,  51  mm  long,  is  placed  on  the  end  of  a  brass  tube  sliding  within  another 
tube  attached  to  the  iron  top.  The  divided  head  regulating  the  width  of  slit  is  graduated  to  read  0.025  mm- 
For  strong  light  sources,  a  slit  width  of  0.075  mm  was  regularly  used.  When  the  30-foot  arrangement 
is  in  use,  the  light  passes  from  the  slit  to  an  8-inch  (20.3  cm)  visually  corrected  objective  by  Brashear, 
which  lies  horizontally  in  a  holder  capable  of  being  moved  vertically  for  focusing  by  turning  a  rod  pass- 
ing to  the  top  of  the  spectrograph  and  rotated  by  a  hand-wheel.  A  metal  box  to  hold  a  plane  grating 
is  just  below  the  lens.  A  rod,  geared  to  the  grating  box  and  passing  above  to  a  second  wheel  at  the 
top  of  the  instrument,  permits  the  rotation  of  the  grating  about  a  horizontal  axis  to  obtain  the  order 
or  region  of  spectrum  desired.  Scales  which  show  the  position  of  the  lens  and  the  inclination  of  the  grat- 
ing can  be  read  by  a  small  telescope  at  the  top  of  the  instrument  when  illuminated  by  incandescent 
lamps  turned  on  from  above.  The  light  reflected  by  the  grating  passes  again  through  the  lens  and  the 
spectrum  is  brought  to  a  focus  above,  the  middle  of  the  photographic  plate  lying  in  the  same  plane  as 
the  slit.  The  holder  carrying  the  plate  rests  in  an  iron  frame  supported  at  its  center  so  that  by  tilting 
the  plate-holder  good  focus  can  usually  be  obtained  over  the  whole  of  the  plate,  which  is  17  inches  (43  cm) 
long  and  3.62  inches  (9.2  cm)  wide.  The  plate-holder  can  also  be  moved  parallel  to  itself  by  means 
of  a  rack  and  pinion  to  permit  the  photographing  of  successive  spectra.  Two  shutters,  sliding  horizon- 
tally, are  placed  7.5  mm  below  the  plate  and  can  be  adjusted  to  shut  out  all  light  except  the  strip  of 
spectrum,  the  width  of  which  is  regulated  by  the.length  of  slit  used.  Light  reflected  from  the  lens  sur- 
faces would  reach  the  plate  were  it  not  for  these  shutters  and  for  the  fact  that  a  narrow  bar  is  laid  across 
the  center  of  the  lens  so  as  to  cut  off  the  reflected  rays  which  would  enter  through  the  opening  of  the 
shutters.  With  the  30-foot  focal  length,  a  slight  inclination  of  the  objective  removed  the  reflections 
without  appreciably  affecting  the  definition. 

The  arrangement  of  lens  and  grating  to  give  the  spectrograph  a  focal  length  of  13  feet  (4  m)  follows 
the  plan  of  that  for  the  longer  focus.  The  movements  of  lens  and  grating  are  regulated  by  the  same 
rods  which  control  those  below.  The  grating-holder  may  be  moved  over  to  the  side  of  the  steel  frame 
and  the  lens-holder  swung  back  out  of  the  way  when  the  30-foot  arrangement  is  desired. 

The  two  plane  gratings  used  during  the  investigation  were  a  Rowland  grating  12.5  cm  long  and  9  cm 
wide,  having  568  lines  to  the  millimeter  and  a  Michelson  grating  19  cm  long  by  7.2  cm  wide,  having  500 
lines  per  mm.  The  former  was  used  with  the  i3-foot  arrangement  for  the  majority  of  the  plates.  The 
Michelson  grating  was  obtained  near  the  end  of  the  investigation  and  a  number  of  the  later  plates  were 
taken  with  this,  which  was  adjusted  for  the  3o-foot  focus.  While  longer  exposure  must  be  used  with  the 
longer  focus,  the  large  scale  is  very  desirable  and  the  field  is  much  flatter,  so  that  as  a  rule  the  whole 
length  of  spectrum  over  a  1 7-inch  (43  cm)  plate  can  be  obtained  in  fair  focus,  even  in  the  first  order. 
For  very  weak  light-sources,  however,  the  13-foot  arrangement  often  gives  better  results,  as  there  may 
be  unavoidable  changes  in  either  the  source  or  the  spectrograph  if  the  exposure  is  greatly  prolonged. 

The  scales  of  the  photographs  for  the  two  focal  lengths  and  the  several  orders  used  in  this  work  are 
approximately  as  shown  in  the  small  table  on  the  following  page,  there  being  a  variation  in  the  second 
decimal  place  according  to  the  part  of  the  spectrum  observed. 

Other  important  features  of  the  spectrograph  are  the  occulting  plate  of  the  slit,  the  mirror  support, 
and  the  polarizing  apparatus.  Plate  II  shows  the  form  of  the  occulting  plate.  It  is  of  brass,  dull  silver- 
plated,  and  supported  on  four  pins  screwed  into  the  top  of  the  spectrograph,  so  that  it  is  entirely  free 


APPARATUS  AND  METHODS. 


Focus. 

ORDER. 

o 

ANGSTROMS 

PER  MM. 

13  foot 

Second 

2.05 

13  foot 

Third 

i-35 

30  foot 

First 

1.92 

30  foot 

Second 

°-95 

30  foot 

Third 

0.60 

30  foot 

Fourth 

o-45 

from  the  slit,  and  about  2  mm  above  the  latter.  By  moving  the  V-shaped  opening  a,  by  means  of  the 
rack  and  pinion,  any  length  of  slit  up  to  n  mm  may  be  obtained.  A  further  movement  brings  the 
double  opening  b,  whose  size  may  be  adjusted  by  the  sliding  plate  c,  over  the  slit.  By  a  proper  setting 
of  the  scale  d,  a  double  comparison  spectrum  can  thus  be  placed  outside  that  made  with  the  opening  a 
without  risk  of  instrumental  displacement,  since  the  plate-holder  and  all  essential  parts  of  the  spectro- 
graph  are  left  untouched. 

Plate  II  shows  the  arrangement  of  the  mirror  by  which  the  light  coming  horizontally  from  any  piece 
of  apparatus  in  the  laboratory  is  reflected  to  the  slit  of  the  spectrograph.  The  holder  for  the  mirror,  which 
is  of  plate  glass  12.5  cm  in  diameter,  silvered  on  its  front  surface,  can  be  turned  about  a  horizontal  axis, 
and  is  supported  at  the  lower  end  of  a  brass  cylinder.    This  cylinder 
can  either  rotate  or  move  up  and  down  inside  a  stationary  cylinder  held 
in  position  by  three  curved  iron  supports  which  are  screwed  to  the  top 
of  the  spectrograph.     The  mirror  may  thus  be  placed  in  any  position 
necessary  to  direct  the  beam  into  the  instrument.    As  the  mirror  can  be 
turned  in  any  direction  independently  of  the  spectrograph,  we  may  have 
any  desired  orientation  of  the  slit  with  respect  to  the  light  source,  which 
is  usually  out  of  the  question  with  a  spectrograph  mounted  horizontally. 
This  is  a  very  great  advantage  in  an  instrument  free  from  astigmatism. 

For  the  Zeeman  photographs  the  slit  was  regularly  used  parallel  to  the  lines  of  force  of  the  magnet. 
In  photographing  arc  and  spark  spectra  in  general,  it  is  desirable  to  use  the  slit  sometimes  parallel, 
sometimes  perpendicular  to  the  direction  of  discharge  in  the  image  projected  upon  it. 

The  Nicol  prism,  by  which  the  light  polarized  in  one  plane  is  transmitted  to  the  slit,  is  held  on  a  metal 
platform  3.5  cm  above  the  slit.  The  Nicol  prism  which  has  been  used  thus  far  was  loaned  by  Director 
Stratton  of  the  National  Bureau  of  Standards.  The  diagonals  of  the  face  are  25  and  30  mm  and  the  prism 
is  6.5  cm  long.  It  is  held  in  a  brass  cylinder  having  a  graduated  circle  by  which  the  Nicol  can  be  set  at  any 
desired  angle  to  the  plane  of  polarization  of  the  incident  light.  A  second  platform  can  be  placed  above 
the  Nicol  to  hold  a  Fresnel  rhomb  when  this  is  desired  for  the  study  of  circular  polarization. 

Since  the  beam  passing  through  the  Nicol  is  displaced  parallel  to  itself,  when  the  prism  is  rotated  90° 
to  transmit  the  other  Zeeman  component  the  image  does  not  remain  on  the  slit.  The  image  is  then  brought 
back  by  moving  the  focusing  lens,  a  simple  glass  lens  of  58.4  cm  focal  length  and  10  cm  diameter.  After 
such  a  change,  it  was  always  noted  whether  the  grating  was  well  centered  in  the  beam  of  light,  which 
usually  had  at  least  three  times  the  diameter  of  the  spectrograph  objective.  Although  small  movements 
of  a  focusing  lens  of  the  focal  length  used  produce  very  slight  changes  in  the  direction  of  the  beam  to  the 
grating,  still  care  was  taken  never  to  move  the  lens  when  an  instrumental  displacement  of  the  spectrum 
lines  could  have  any  disturbing  effect.  After  an  exposure  with  the  magnetic  field,  the  only  change  before 
starting  the  exposure  for  the  spark  without  field  was  to  move  the  occulting  plate  above  the  slit,  so  that 
the  comparison  spectrum  would  be  on  each  side  of  the  spectrum  taken  with  the  field.  The  light  source 
thus  remained  unchanged  in  position,  and  all  parts  of  the  optical  system  as  well  as  the  photographic 
plate  were  left  untouched. 

The  spectrograph  remains  in  adjustment  for  longer  periods  probably  than  with  any  mounting  other 
than  the  vertical  arrangement  in  a  well.  The  temperature  change  at  the  bottom  of  the  well  is  entirely 
negligible  during  short  periods  of  time.  A  recent  test  showed  that  during  three  months  in  which  tem- 
perature variations  of  over  15°  C  were  experienced  in  the  laboratory,  a  thermometer  placed  beside  the 
grating  rose  very  gradually  from  i8°6  to  i9°o  C.  During  this  time  the  lights  were  frequently  turned 
on  to  read  the  adjustment  scales,  and  there  were  occasional  visits  by  observers  to  the  bottom  of  the  well. 
Mechanical  vibrations  are  more  disturbing.  It  has  been  necessary  to  close  the  driveway  beside  the 
laboratory  during  exposures  with  the  spectrograph,  and  to  take  care  that  no  machinery  be  used  which 
would  transmit  a  vibration  to  the  spectrograph  mounting. 


1 6         INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

4.  PHOTOGRAPHIC  METHODS. 

The  requirements  as  to  photographic  plates  in  an  investigation  of  this  sort  are  to  some  extent  con- 
flicting. Speed,  a  fairly  fine  grain,  good  latitude,  so  that  weak  lines  may  be  obtained  without  serious 
over-exposure  of  the  stronger  ones,  together  with  enough  contrast  to  give  sharply  defined  lines,  are  ele- 
ments not  easily  combined  in  one  plate.  A  number  of  plates  have  been  tried,  including  the  Lumiere 
"Sigma,"  the  Seed  "Gilt  Edge  27,"  "23,"  and  "Process,"  the  Cramer  "Crown"  and  "Inst.  Isochro- 
matic."  Each  kind  of  plate  will  give  superior  effects  for  a  certain  type  of  line;  but  in  general  I  have 
obtained  the  best  results  for  the  work  from  the  Seed  "Gilt  Edge  27"  for  the  blue  end  of  the  spectrum  as 
far  as  about  \46oo,  and  from  there  on  into  the  red  from  the  same  plate  bathed  with  the  solution  of  pina- 
cyanol,  pinaverdol,  and  homocol  recommended  by  Wallace  (55).  This  plate  is  the  best  adapted  of  those 
I  have  tried  in  regard  to  doing  justice  to  all  classes  of  lines.  It  is  a  fast  plate  without  an  objectionably 
coarse  grain.  The  latitude  is  good.  In  the  case  of  lines  of  complex  Zeeman  separation,  a  plate  with  more 
contrast  will  often  fail  to  show  weak  components  very  close  to  stronger  ones. 

A  properly  chosen  developer  will  sharpen  the  lines  to  a  great  extent,  avoiding  troublesome  shad- 
ing off  from  the  central  maximum.  After  trying  several  solutions,  I  have  preferred  a  hydroquinone 
developer  giving  strong  contrast,  due  to  Mr.  Wallace,  but  not  published  so  far  as  I  know.  The  propor- 
tions are  as  follows,  using  equal  parts  of  A  and  B : 

Solution  A:  Solution  B: 

Water. ...  48  oz.  Water 48  oz. 

Hydroquinone  640  grains  Carbonate  soda  (anhydrous)    I  oz. 

Sulphite  soda  (anhydrous) i  oz.  Carbonate  potassium  (anhydrous) 4  oz. 

Sulphuric  acid  (cone.) 30  drops  Bromide  potassium %  oz. 

This  developer  does  not  stain  the  plates,  even  when  warm.  Development  was  usually  carried  to  the 
point  where  chemical  fog  sets  in.  This  comes  on  slowly,  and  the  solution  is  as  efficient  in  bringing  up 
weak  images  as  any  I  have  tried.  When  used  at  20°  C  a  bathed  plate  is  usually  fully  developed  in  6  to 
7  minutes.  Some  very  good  photographs  were  obtained  for  the  region  \52oo  to  \55oo  by  the  use  of  the 
Cramer  "Inst.  Isochromatic";  but  it  was  found  best  to  soften  its  contrast  by  the  use  of  a  metol-hydro- 
quinone  developer.  For  the  region  \48oo  to  ASIOO,  where  the  "Isochromatic"  is  weak,  as  well  as  for 
the  whole  of  the  orange  and  red,  the  action  of  the  bathed  "27"  has  been  unsurpassed  by  any  plate  used 
in  these  experiments. 

5.  MEASUREMENT  OF  MAGNETIC  FIELD. 

The  accurate  measurement  of  field-strength  presented  some  difficulties  in  the  case  of  iron  on  account 
of  the  use  of  metallic  terminals  for  the  spark.  The  field  for  titanium  was  more  easily  obtained,  and  was 
based  on  direct  measurements  by  a  bismuth  spiral.  This  instrument  was  obtained  from  Hartmann  and 
Braun,  but  instead  of  using  the  regular  formula  for  temperature  correction,  the  spiral  was  sent  to  the 
National  Bureau  of  Standards  and  there  calibrated  to  provide  a  series  of  curves  for  the  variation  of  field- 
strength  with  change  of  resistance  for  temperatures  of  15°,  20°,  25°,  30,°  and  35°  C.  When  used  at  inter- 
mediate temperatures  the  interpolation  was  simple.  The  resistance  in  and  out  of  the  field  was  measured 
with  a  Kohlrausch  bridge. 

A  set  of  plates  of  the  titanium  spectrum,  extending  over  the  whole  region  investigated,  was  taken 
with  the  magnetic  field  as  nearly  the  same  as  possible.  All  parts  of  the  magnet  were  left  unchanged 
and  the  same  current  was  used  throughout.  By  check  measurements  with  the  bismuth  spiral  and  by 
comparison  of  plates  which  overlapped  enough  to  measure  some  of  the  same  lines  on  both,  it  appeared 
that  a  field-strength  of  17,500  gausses  was  maintained  for  this  set  with  a  variation  no  greater  than  200 
gausses.  Other  photographs  taken  to  supplement  the  measurement  of  certain  regions  had  their  values 
reduced  to  correspond  to  a  field-strength  of  17,500  by  comparison  of  the  separations  of  sharply  defined  lines. 

For  the  iron  spectrum  it  is  well  known  that  indirect  methods  must  be  used  to  determine  the  field- 
strength,  since  the  use  of  iron  spark  terminals  distorts  the  field  to  such  an  extent  that  any  object  as  large 


APPARATUS  AND  METHODS.  I  7 

as  the  bismuth  spiral  or  an  exploring  coil  for  the  ballistic  method  will  not  give  true  values  for  the  field 
to  which  the  spark  vapor  is  subjected.  It  may  be  that  the  iron  vapor,  when  sufficiently  dense,  has  an 
appreciable  permeability  of  its  own.  There  is,  however,  no  evidence  on  this  point. 

The  plates  for  the  iron  spectrum  were  taken  at  intervals  extending  over  a  year,  during  which  various 
changes  were  made  in  the  experimental  arrangements  which  involved  changes  in  the  magnetic  field. 
However,  a  considerable  region  in  the  blue  and  violet  was  photographed  with  the  same  field,  and  the  pub- 
lication of  Mrs.  van  Bilderbeek  (49)  gave  an  opportunity  to  make  a  comparison  with  her  values.  In  her 
work  some  photographs  were  taken  using  a  spark  with  one  iron  and  one  zinc  terminal,  thus  obtaining  the 
zinc  triplet  X 4680.3 17,  as  well  as  some  iron  lines  in  that  region.  Weiss  and  Cotton  (20)  by  a  series  of  very 
careful  measurements  obtained  the  relation  AX/HX2=  1.875  x  IO  4  f°r  the  separation  of  the  outer  compo- 
nents of  this  triplet,  from  which  Mrs.  van  Bilderbeek  deduced  the  value  32,040  gausses  for  the  standard 
field  which  she  used  when  iron  terminals  alone  were  employed.  I  was  able  to  select  from  my  list  33  lines 
between  the  limits  X37oo  and  X44OO,  which  are  also  given  in  Mrs.  van  Bilderbeek's  table,  in  nearly  all 
cases  clear  triplets,  for  which  my  measurements  are  of  high  weight.  The  ratio  between  Mrs.  van  Bilder- 
beek's values  and  mine  for  these  lines  was  in  every  case  very  close  to  2,  the  greatest  deviation  being  given 
by  the  value  2.14.  The  mean  ratio  for  the  lines  is  2.01,  giving  a  value  of  15,940  gausses  for  the  field  used 
by  me  in  photographing  the  iron  spectrum.  This  is  in  very  satisfactory  agreement  with  a  value  which 
I  had  already  determined  by  photographing  the  strong  line  X 4383. 7 20  as  given  by  a  spark  between  car- 
bon terminals  on  which  a  little  iron  solution  was  placed  in  a  field  measured  by  the  bismuth  spiral  as 
17,600,  and  comparing  the  separation  with  that  of  the  components  of  the  same  line  very  sharply 
photographed  with  iron  terminals  used  in  the  standard  field.  Exactly  the  same  value  was  given  by  com- 
paring the  separation  of  X 4383. 7 20  in  two  photographs,  one  with  iron  poles,  the  other  in  which  the  line 
came  up  as  an  impurity  in  a  titanium  photograph  taken  with  the  standard  titanium  field  of  17,500. 
Assuming  that  the  value  of  the  field  for  iron  was  established  by  the  other  measurements,  this  last  test 
gave  an  excellent  check  on  the  standard  field  for  titanium,  which  would  otherwise  depend  on  the  meas- 
urement with  the  bismuth  spiral.  It  would  seem  then  that  the  value  of  16,000  gausses  can  be  safely 
taken  for  the  standard  iron  field  with  an  error  less  than  i  per  cent.  A  considerable  number  of  photo- 
graphs for  both  iron  and  titanium  were  made  with  fields  close  to  20,000  gausses,  sometimes  slightly 
higher,  but  the  measurements  were  reduced  to  correspond  to  fields  of  16,000  and  17,500,  respectively. 

A  similar  system  of  checking  field-strengths  was  applied  for  the  region  to  the  red  of  X44oo.  A  spark 
was  used  with  one  terminal  of  iron  and  the  other  of  brass.  Two  photographs  were  taken  in  which  the 
zinc  triplet  X  4680.3 1 7  appeared  as  well  as  a  number  of  iron  lines,  among  them  the  wide  and  sharp 
triplet  X4878.407.  Using  the  value  of  Weiss  and  Cotton,  the  field-strength  for  the  measured  separation 
of  this  iron  line  (20,360  gausses  for  AX=  1.389  A)  was  deduced.  Spark  terminals  of  the  same  kind  with 
all  parts  of  the  magnet  unchanged  were  then  used  for  a  series  of  photographs  covering  the  iron  spec- 
trum as  far  as  X67oo.  The  field  was  thus  kept  as  nearly  constant  as  possible,  and  by  comparing  the 
separations  of  iron  lines  with  this  known  field  with  those  on  former  plates  taken  with  various  fields  it  was 
possible  to  reduce  all  values  for  the  iron  spectrum  to  the  standard  field  of  16,000. 

6.  METHODS  OF  MEASUREMENT  AND  REDUCTION. 

The  measurement  of  the  earlier  plates  was  carried  out  by  Miss  Wickham,  while  the  later  plates  were 
measured  by  Miss  Griffin.  The  machine  used  was  a  small  Gaertner  comparator  having  a  range  of  8  cm, 
the  divided  head  reading  to  o.ooi  mm.  The  process  of  measurement  included  the  identification  of  lines, 
the  determination  of  the  reduction  factor  for  the  portion  of  the  plate  under  examination  and  the  measure- 
ment of  the  separation  of  the  Zeeman  components. 

Various  tables  were  used  in  the  identification  of  lines.  For  the  iron  spectrum  the  tables  of  Kayser 
and  Runge  (56)  for  the  iron  arc  were  supplemented  by  those  of  Exner  and  Haschek  (57)  for  the  spark, 


1 8          INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

also  by  the  list  of  enhanced  lines  given  by  Lockyer  (58)  and  by  plates  of  the  arc  and  spark  spectra  of  iron 
taken  in  this  laboratory.  For  the  titanium  spectrum  the  tables  and  charts  of  Hasselberg  (59)  were  use- 
ful as  far  as  X  5900.  This  was  supplemented  for  the  red  end  by  the  measures  of  arc  lines  by  Fiebig  (60) . 
The  spark  tables  of  Exner  and  Haschek  and  of  Lockyer  were  used  as  for  iron.  The  identifications  of 
solar  lines  in  Rowland's  Tables  are  in  most  cases  so  close  to  the  values  in  the  tables  of  arc  and  spark 
spectra  that  there  is  no  doubt  of  the  correspondence  of  the  lines.  The  wave-lengths  given  in  this 
publication  are  entirely  on  the  Rowland  system. 

The  chart  of  the  iron  arc  spectrum  by  Buisson  and  Fabry  (61)  was  of  great  assistance  in  the  approxi- 
mate identification  of  lines,  the  scale  being  almost  the  same  as  that  of  my  plates  taken  in  the  third  order 
with  the  i3-foot  focal  length.  In  addition  to  using  this  chart  for  the  iron  spectrum,  it  served  also  for 
titanium  when  used  in  conjunction  with  a  set  of  plates  which  I  made  of  the  spectra  of  the  titanium  spark 
and  iron  arc  side  by  side. 

The  definitive  identification  of  lines  was  in  the  usual  way  by  measurement  from  neighboring  lines 
whose  identity  was  certain.  On  account  of  the  incompleteness  of  the  general  tables  of  spectra  for  the 
red  region,  a  few  lines  are  entered  in  my  titanium  table  which  may  belong  to  other  substances.  Some 
of  these,  in  all  probability,  are  lines  given  stronger  in  the  spark  than  in  the  arc,  which  explains  their 
absence  from  Fiebig's  list.  The  doubtful  origin  of  such  lines  is  indicated  in  the  column  headed  "Remarks." 

The  spectrum  given  by  the  plane  grating  spectrograph  not  being  quite  normal,  the  reduction  factor 
of  the  plate,  expressed  in  Angstrom  units  per  millimeter,  was  determined  at  intervals  usually  of  2  to  3  cm. 
The  change  in  the  factor  between  successive  determinations  was  thus  almost  always  less  than  5  in  the 
third  decimal  place.  This  factor  was  multiplied  by  the  distance  in  millimeters  between  the  Zeeman 
components,  which  was  the  mean  of  at  least  four  differential  measurements  taken  alternately  right  and 
left,  setting  first  on  one,  then  on  the  other  of  the  components  whose  separation  was  desired.  The  accu- 
racy of  setting  on  first-class  lines  was  usually  well  within  0.005  mm-  From  such  lines  there  are  all  grada- 
tions up  to  those  for  which  the  measurements  recorded  can  be  taken  only  as  indicating  the  order  of  mag- 
nitude of  the  separation.  Frequently  a  line  has  its  components  on  one  side  blended  with  those  of  an 
adjacent  line.  In  such  a  case  it  is  usually  possible  to  make  a  more  or  less  accurate  measurement  of  half 
the  separation  by  measuring  from  the  clear  component  to  the  no-field  line  which  was  always  photo- 
graphed in  juxtaposition.  The  accuracy  of  measurement  will  be  discussed  further  in  the  explanation 
of  the  tables  when  the  weight  of  measurements  is  considered. 

After  measurement  by  a  member  of  the  Computing  Division  each  plate  was  carefully  gone  over  by 
the  author.  In  this  examination  the  identification  of  lines  was  checked,  the  character  of  the  separation 
and  weight  of  the  measurement  as  determined  by  the  quality  of  the  line  were  decided  upon,  and  many 
check  measurements  with  the  machine  were  made,  including  all  measures  for  determination  of  the  mag- 
netic field  by  a  comparison  of  the  separation  of  lines  on  different  plates. 


EXPLANATION  OF  THE  TABLES, 
i.  WAVE-LENGTHS. 

The  wave-lengths  given  in  the  first  column  are  on  the  Rowland  system.  The  methods  of  identifi- 
cation and  the  tables  used  have  been  treated  in  the  preceding  section. 

2.  INTENSITY. 

This  column  is  intended  to  give  an  approximate  value  of  the  intensity  of  the  lines  in  the  spark  spec- 
trum. The  numbers  are  taken  (with  occasional  modifications)  from  the  tables  of  Exner  and  Haschek 
for  the  spark  spectrum  as  far  as  X47oo,  beyond  which  the  intensities  were  estimated  on  the  same  scale 
from  my  plates.  Weak  lines  are  graded  "  i "  on  this  scale,  but  there  is  considerable  variation  in  the  strength 
of  lines  which  are  given  this  value.  For  the  purposes  of  this  paper,  this  grading  of  intensities  is  sufficient. 

3.  CHARACTER  OF  SEPARATION. 

In  this  column  is  described  the  type  of  separation  of  each  line  when  the  n-  and  ^-components*  are 
combined,  as  is  the  case  when  the  light  of  the  spark  is  observed  at  right  angles  to  the  magnetic  force- 
lines  without  Nicol  or  other  apparatus  to  separate  the  light  vibrating  in  the  two  directions.  Thus  in 
the  reproductions  the  two  portions  of  each  spectrum  showing  the  effect  of  the  magnetic  field  should  be 
superposed  to  give  the  appearance  of  the  line  as  described  in  this  column. 

The  description  gives  the  best  judgment  of  the  type  of  separation  that  can  be  made  from  the  photo- 
graphs. It  must  be  considered  in  connection  with  the  measured  separation  and  widening  of  components 
given  in  the  columns  for  AX  of  the  n-  and  ^-components,  and  is  usually  made  clear  by  these.  Frequently 
a  supplementary  remark  is  needed  in  the  case  of  complex  lines. 

A  line  designated  as  triple  has  its  one  p-  and  two  w-components  of  sufficient  sharpness  to  give  no  indi- 
cation that  any  of  them  are  compound.  Since  the  Zeeman  components  follow  to  some  extent  the  general 
character  of  the  spectrum  line,  when  a  line  is  itself  wide  and  diffuse,  its  components  may  be  simple  and 
still  not  so  sharp  as  those  of  lines  which  do  not  tend  to  diffuseness.  The  proximity  of  the  no-field  line  on 
the  plate  aids  in  the  judgment  of  such  cases,  but  some  of  them  are  uncertain  at  the  best.  The  tendency 
of  some  lines  to  reverse  is  very  disturbing  in  this  connection,  since  it  is  very  difficult  to  obtain  such  lines 
with  really  sharp  components.  Several  iron  lines  between  \37oo  and  \39OO,  which  give  wide  reversals 
in  the  arc  and  spark  between  iron  terminals,  can  be  made  to  show  the  Zeeman  components  also  reversed, 
by  the  use  of  a  strongly  condensed  spark,  so  that  a  triplet  appears  as  a  sextuplet.  To  decide  such  cases 
it  was  necessary  to  make  special  photographs,  using  much  self-induction  and  also  with  carbon  terminals 
containing  a  little  iron.  The  titanium  photographs  were  also  useful  in  this  connection,  since  the  titanium 
used  contained  enough  iron  to  give  the  stronger  iron  lines  which  appear  with  sharp  components  under 
such  conditions. 

The  interrogation  point  is  very  freely  used  to  indicate  that  the  line  is  probably  of  the  character  given, 
though  not  clearly  shown  to  be  so  on  the  plates.  The  reason  for  doubt  is  usually  given  in  the  columns 
for  AX.  Thus  "triple?"  means  that  the  /^-component  is  slightly  widened  so  that  it  may  not  be  simple, 
but  still  the  widening  may  be  explained  by  the  strength  of  the  component  or  by  the  fact  that  the  line 

*  n  and  p  are  used  throughout  this  paper  as  abbreviations  of  "normal"  and  "parallel."  n  denotes  the  Zeeman  components 
given  by  light  vibrations  in  a  plane  at  right  angles  to  the  lines  of  magnetic  force,  and  p  those  given  by  vibrations  parallel  to  the  force- 
lines.  The  symbols  correspond  to  the  letters  s  and  p  regularly  used  in  German  publications. 

19 


20  INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

itself  is  slightly  diffuse,  which  may  account  for  the  lack  of  sharpness  in  the  components.  "Quadruple?" 
means  that  the  two  w-components  are  fairly  sharp,  but  the  /(-component  is  probably  double.  A  doubtful 
quintuplet  will  usually  have  five  components  measurable,  with  indications  that  others  are  possibly  present. 
Doubtful  sextuplets  are  very  common.  As  a  rule  such  a  line  has  its  two  w-components  widened  so  that 
there  are  probably  two  pairs,  while  the  /(-component  is  either  distinctly  double,  or  unresolved  and  con- 
siderably widened.  The  decision  between  doubtful  sextuplets  and  septuplets  is  frequently  difficult  and 
often  quite  uncertain.  The  /(-component  in  such  cases  is  not  resolved,  but  the  character  of  its  widening 
will  often  show  whether  it  is  double  or  triple.  A  widening  with  strong  central  maximum  means  usually 
three  /(-components,  but  there  may  be  five.  Such  a  line,  if  it  has  two  widened  w-components,  is  classed 
as  a  probable  septuplet.  Octuplets  and  lines  of  higher  separation  are  classified  in  a  similar  way,  the  widen- 
ing given  in  the  two  AX  columns,  together  with  the  remarks,  showing  in  what  respect  the  given  char- 
acter may  be  doubtful.  Lines  whose  w-components  are  "  fringed ' '  are  difficult  to  classify.  Such  ' '  fringes ' ' 
indicate  very  close,  unresolved  components,  and  these  may  be  numerous.  A  field  double  that  available 
here  would  probably  show  the  full  structure.  Many  lines  were  fully  resolved  by  a  field  of  20,000  which 
had  to  be  described  as  "fringed"  for  a  field  of  16,000.  The  degree  of  widening  due  to  the  fringes  is  given 
in  the  AX  column  and  a  remark  tells  whether  the  fringes  are  toward  the  center  or  outwards.  The  number 
of  components  is  estimated  as  closely  as  possible  from  the  width  of  the  fringes,  but  when  the  structure 
is  very  complex,  an  interrogation  point  is  used  without  any  attempt  to  give  the  number  of  components. 
Although  the  doubtful  elements  which  have  been  mentioned  come  into  the  estimates  as  to  the  char- 
acter of  lines,  the  large  number  of  plates  from  which  the  material  was  taken  gave  an  opportunity  to  study 
each  line  under  various  conditions  of  intensity  and  degree  of  separation,  so  that  the  classification  as  to 
character  is  probably  as  accurate  as  can  be  made  without  very  much  greater  field-strength  combined 
with  as  high  resolving  power  as  was  here  used. 

4.  WEIGHT. 

Under  this  heading,  each  line  for  which  measurement  was  possible  is  given  the  weight  3,  2,  or  i, 
according  as  the  quality  of  the  Zeeman  components  for  measurement  is  good,  fair,  or  poor.  This  grading 
should  be  of  much  service  in  any  use  which  is  made  of  these  tables.  In  attempts  which  the  author  has 
made  to  compare  his  measurements  with  those  of  others,  the  discordances  were  nearly  always  found  to 
occur  in  the  case  of  lines  of  such  character  that  one  or  both  sets  of  measurements  were  poor.  If  lines 
of  high  weight  in  each  set  are  compared,  a  good  check  on  the  observations  is  obtained. 

Lines  of  weight  3  have  sharply  defined  components,  and  for  such  lines  measurements  of  the  same 
plate  by  different  observers  or  different  sets  by  the  same  observer  usually  give  differences  in  the  third 
decimal  place  only,  while  for  many  lines  of  this  class  the  probable  error  is  not  greater  than  two  or  three 
thousandths  of  an  Angstrom.  Only  lines  of  weight  3  should  be  used  in  comparisons  of  field-strength. 

Lines  are  weighted  2,  when  the  line  is  reasonably  strong,  because  the  components  are  widened  and 
probably  compound,  fringed,  or  perhaps  single  and  poorly  defined  for  some  reason,  so  that  the  measure- 
ment is  not  so  close  as  for  lines  weighted  3.  Measurements  of  weight  2  have  usually  a  probable  error 
not  greater  than  10  per  cent  and  may  be  used  for  quantitative  comparisons  where  a  high  degree  of  pre- 
cision is  not  required.  When  a  component  is  measured  from  the  no-field  line,  it  is  never  weighted  higher 
than  2.  A  line  whose  components  are  uniformly  widened,  each  consisting  of  two  or  more  components 
of  about  equal  intensity,  gives  a  better  measurement  than  a  line  whose  components  are  fringed,  since 
in  the  latter  case  photographic  conditions  affect  the  distinctness  of  the  maximum  of  each  shaded  com- 
ponent, this  maximum  being  the  part  measured. 

Weight  i  is  given  to  lines  which  are  very  faint,  much  disturbed  by  blends,  or  of  such  complex  struc- 
ture that  the  components  are  extremely  diffuse.  The  error  of  measurement  for  such  lines  may  be  large 
and  the  three  decimal  places  are  entered  only  for  the  sake  of  uniformity.  However,  the  figures  given 


EXPLANATION  OF  THE  TABLES.  2  I 

show  whether  the  line  is  to  be  classed  as  having  small,  medium,  or  large  separation,  and  for  this  reason 
the  inclusion  of  such  lines  is  justified. 

When  measurements  are  given  for  both  the  n-  and  the  ^-components,  the  weight  for  each  is  given, 
separated  by  a  comma.  In  case  only  the  p-component  is  measured,  a  dash  before  the  comma  indicates 
the  omission  of  the  weight  for  the  w-component. 

5.  VALUES  OF  AX. 

The  fifth  and  sixth  columns  of  the  tables  contain  the  separation  in  Angstrom  units  of  the  components 
given  by  light  vibrating  respectively  perpendicular  and  parallel  to  the  lines  of  magnetic  force.  (See 
foot-note,  p.  19.)  When  there  is  an  even  number  of  components  for  the  same  polarization,  measurements 
are  made  between  the  members  of  each  pair  which  presents  itself.  A  single  value  in  one  of  these  columns 
means  that  one  pair  of  components  is  present.  When  there  are  two  or  more  pairs,  the  largest  separa- 
tion is  given  first,  but  the  innermost  pair  is  designated  "Pair  I."  When  there  is  an  odd  number  of  com- 
ponents, any  outer  ones  that  may  appear  are  measured  from  the  central  component,  instead  of  being 
treated  as  pairs,  and  the  values  are  listed  beginning  with  the  outermost  on  the  violet  side,  the  presence 
of  a  central  component  being  indicated  by  o.ooo.  No  attempt  is  made  to  give  the  relative  intensity  of 
the  n-  and  ^-components,  as  this  depends  largely  upon  the  optical  system.  However,  if  there  are  more 
than  two  components  for  the  same  polarization,  the  relative  intensity  of  the  pairs  (or  of  each  component 
when  there  is  an  odd  number)  is  given  in  parentheses  after  the  value  of  the  separation. 

If  either  AX  column  is  blank  for  a  certain  line,  this  indicates  that  a  single,  sharp  component  appears 
for  this  polarization.  Thus  for  all  clear  triplets,  the  ^-component  column  is  blank.  If,  however,  the 
^-component  is  unresolved,  but  widened  so  as  to  indicate  that  a  higher  field  would  separate  it  into  two 
or  more,  the  letter  "w"  with  subscript  i,  2,  or  3  is  used  to  show  the  degree  of  widening.  Components 
marked  "w2"  or  "w3"  as  a  rule  are  certainly  compound.  A  slight  widening,  which  probably  means  more 
than  one  component,  is  indicated  by  "wu"  but  this  may  in  some  cases  result  from  the  diffuse  character 
of  the  no-field  line. 

There  are  many  cases,  especially  in  the  w-component  column,  where  a  measurement  is  given,  followed 
by  "w"  with  a  subscript.  This  means  that  a  pair  is  measured,  but  each  member  of  the  pair  is  widened  and 
probably  compound.  If  the  widening  is  uniform,  there  are  probably  two  or  more  components  of  equal 
intensity.  If  the  constituents  of  the  widened  component  are  of  different  intensity  the  component  is 
shaded  toward  one  side.  Such  a  line  has  the  degree  of  widening  given  and  in  addition  is  denoted  in 
the  "Remarks"  column  as  "fringed"  when  each  component  shades  off  from  the  center,  or  as  having 
"inner  fringes"  when  the  shading  is  toward  the  center. 

The  letters  "n.m."  indicate  that  a  separation  exists  but  is  not  measurable,  usually  by  reason  of  the 
faintness  of  the  components.  In  such  cases  it  is  possible,  as  a  rule,  to  tell  the  character  of  the  separation 
with  fair  certainty  and  the  line  is  included  on  this  account.  Thus  a  faint  but  sharp  ^-component  com- 
bined with  traces  of  two  sharp  w-components  is  given  as  a  triplet.  The  designation  "n.m.w."  is  used 
when  the  components  are  hazy  as  well  as  faint. 

6.  VALUES  OF  AX/X2. 

Since  in  most  points  relating  to  the  theory  of  the  Zeeman  phenomenon,  the  values  of  AX/X2  rather 
than  of  AX  are  considered  (p.  4),  the  former  quantity  is  entered  in  the  seventh  and  eighth  columns, 
the  positions  of  the  numbers  in  the  column  being  the  same  as  that  of  the  corresponding  values  of  AX. 
When  X  is  in  Angstrom  units,  the  values  given  for  AX/X2  are  to  be  multiplied  by  icr8. 


2  2  INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

TABLE  i. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON. 


g 

en 

CHARACTER 

| 

A' 

V 

AX 

A2 

HH 

SEPARATION. 

o 

1 

W-COMP. 

^-COMP. 

K-COMP. 

p-COMF. 

36^0  663 

I 

Triple 

2 

o  176 

I  .  314 

Triple? 

2 

Wl 

I    3O7 

3670.240 

2676    4<J7 

I 
I 

Quadruple? 
Triple 

2 

7, 

0.26lWl 

o  236 

W2 

1.938 
I    .746 

Triple 

i  o6< 

Faint  in  spark 

3677.764 

7670   OO2 

2 

I 

Triple 
Triple 

3 

i 

0.167 
o  268 

1.234 
i  .980 

Faint  in  spark 

3680  .  069 
3682  2.82 

3 
i 

Sextuple? 
Triple 

3,3 

2 

0  .  296  W2 

O    23O 

O.III 

2.186 
i  .696 

0.820 

Sextuple? 

3     C7Q 

;z-comps.    have    inner    fringes 

3684  2?8 

Triple? 

7, 

O    I7O 

Wi 

I    2<C2 

/>-comps.  almost  resolved 

3686  141 

2 

Sextuple? 

2 

O    I94  W2 

W2 

1.428 

n-  and  />-comps.  diffuse 

Triple 

2    286 

3689.614 
3690.870 

2 

I 

Sextuple? 
Sextuple? 

? 

2,1 
2,1 

0.373  Wi 
0  .  268  Wi 

0.097 
0.096 

2-739 
1.967 

2    23? 

0.712 
0.705 

H-comps.  fringed.      Probably  4 

Triple 

/>-comps.  blended 

3697-567 

I 

Sextuple? 
? 

-,I 

2 

n.m.  Ws 

0-345 

I    723 

2.522 

w-comps.  very  diffuse.    Probably 
more  than  4 
H-comps.   fringed.     Probably   4 

3702  .  170 

I 

Triple 

2 

o  2.1  1; 

2    2o8 

/>-comps.  blended 

Triple' 

2 

2    428 

37O3   062 

1 

Triple 

Faint 

3704  603 

2 

Triple? 

7 

O    3IO 

Wi 

2    324 

3705.708 

3707.186 
3707.959 
3708  068 

4 

I 
I 

4 

8  or  10 
comps. 
Quadruple 
Quadruple 
Sextuple? 

2,3 

2,1 
2,1 
2 

0  .  294  W2 

0,282 
0.627 

O    3  I  <  Wi 

0.147 

0.250 
0.306 

Wi 

2.  141 

2.052 

4.560 
2    2QI 

1.070 

1.819 

2.225 

Probably  3  pairs  n-comps.    May 
be  2  pairs  p-comps. 

Blend  with  3708.068 
«-comps.  fringed 

3709.389 

4 

Triple 

3 

O    3.12 

2    268 

37  1  1    ^64 

i 

Triple 

2 

i   i;68 

3716.054 

i 

2 

Quadruple 

1,1 

0.290 

0.146 

2.100 
2    8?3 

1-057 

37I8.5S4 

I 

Quintuple? 

1,1 

'  -*y4   ,    , 

0.271    (i) 

o  ooo  (2) 

0.286 

1.960 

O    OOO 

2.068 

Unsymmetrical.    Probably  3  n-, 
2  p-comps.     Red  H-comp.  not 

? 

? 

measurable.   Red  />-comp.  half 

372O.O84 

TO 

Triple? 

2 

o  268 

I   076 

as  strong  as  violet 
All  comps.  may  be  compound. 

I 

j 

Line     reverses      readily     and 
comps.  are  never  sharp 
Faint  in  spark 

•2722   O7I 

I 

Triple 

I 

I    02O 

Faint  in  spark 

3722.729 

4 

12  comps. 

2,2 

Pair  IV,  0.415  (2) 
Pair  III,  0.311  (3) 
Pair   II   o  2ii  (3) 

Pair  II,  0.195  (5) 
Pair    I,  n.m.     (i) 

2.994 

2.244 
I     <22 

1.407 

3724.    <26 

2 

Triple 

2 

I    84? 

?727  .  778 

5 

Septuple? 

2 

o  318  Wi 

W2 

2    288 

»-comps    have     inner     fringes. 

•27-10  ^34 

i 

Triple? 

I 

Wi 

2    4<I 

Probably  3  p-comps. 
Blend  with  faint  lines 

3731  .093 

T 

Triple 

I 

o  176 

I  .  264 

777.2     <AZ 

2 

Triple 

7. 

2  86< 

3733-469 

3 

Quintuple 

3,3 

0.157  (2) 

0.322 

1.127 

2.3II 

3735-014 
3735-485 
3737-281 

3738.454 
3743-508 

10 

i 
7 

2 

6 

Triple 
Quadruple? 
Septuple? 

Triple 
Octuple 

2 
2,2 
2 

3 

3,3 

0.158(2) 
0.310 

0.472  wi 
0.254  wi 

0.207 
0.208  (4) 
0.104  (2) 
o.ooo  (2) 
0.112  (a) 
0.213  (s) 

0.166 

W2 
0.107   (2) 

o.ooo  (3) 
o.  106  (2) 

1-134 

2.222 
3-384 

1.818 

1.481 
1.484 
0.742 
o.ooo 

0-799 
1.520 

I.I9O 

0.763 
O.OOO 

0.756 

«-comps.  fringed.     Probably  3 
p-comps. 

Comps.  of  faint  line  to  red  (com- 
puted 3743.615)  are  superposed 
on  central  and  outer  red  n- 
comps.  giving    apparent    dis- 
symmetry. Compare  3788.046 

MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON. 


TABLE  i.  —  MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON  —  Continued. 


x 

X 
H 
en 

•5 

CHARACTER 

| 

i 

IX 

A> 

A2 

& 

SEPARATION. 

M 

W-COMP. 

p-COMP. 

»-COMP. 

^>-COMP 

3744.251 

I 

Septuple? 

1,1 

O.4OI   W2 

0.283  (i) 

o  ooo  (i) 

2.861 

2.018 

Probably  4  «-comps.  Apparent- 

0.415  (i) 

Dare  3747 

3745.717 

i; 

Septuple? 

2 

O.  228  Wl 

W2 

1.624 

w-comps   fringed.      Probably  3 

3746.058 
3747-065 

I 

Unaffected 
Septuple? 

1,1 

0.413  w2 

0.306  (i) 
o.ooo  (2) 

2.941 

2.l8o 

p-comps. 
Apparently  same  type  as  3744. 

3748.408 

4 

9  comps.? 

2 

Pair  III,  0.316  (4) 

0-341  (i) 

W3 

2.250 

2.429 

Probably    3    ^-comps.    almost 

Pair   II,  0.226  (3) 

1  .609 

resolved 

Pair     I,  o  101  (i) 

3749.049 

I 

Quadruple? 

2 

o  .  240  wi 

W2 

1.708 

3749.631 

10 

Triple 

2 

0.289 

2  .055 

3753.732 

2 

Triple 

3 

0.395 

2  8oa 

3756.213 

j 

Triple? 

2 

0.300 

Wi 

2.126 

3757.081 

I 

Triple? 

I 

o.  197 

Wl 

i  306 

3757-597 

I 

Triple 

I 

0.388 

2.747 

Faint  in  spark 

3758.375 

8 

Triple 

3 

0.269 

.00? 

f 

3760.196 

2 

Triple 

3 

0.235 

.662 

3760.679 

I 

Quintuple? 

2 

0.146  (i) 

W2 

.032 

«-comp.  appears  as  unsymmet- 

o.ooo  (i) 

o  ooo 

o.  179  (i) 

26<; 

blend 

3763.945 

6 

Triple 

3 

0.218 

°n8 

3765.689 

i, 

Triple 

3 

0.228 

.608 

3767-34I 
3768.173 

5 

T 

Unaffected 
Triple 

2 

0.600 

4    22S 

3770.446 

I 

Triple 

2 

o.  191 

I  .  24.  -2 

3773-803 
3774-971 

I 
I 

Unaffected 
Sextuple 

2,1 

Pair  II,  0.545  (i) 
Pair    I,  0.274  (i) 

0.240 

3.824 
i  .922 

1.684 

/>-comps.  faint 

3776.600 

I 

Triple? 

2 

0.229 

Wi 

i  .  605 

3777-593 
3778.652 

I 
T 

Quadruple? 
Triple 

I 

n.m. 

0.344 

n.m. 

2  .408 

Very  faint.     Wide  separation  of 
p-comp. 

3779.569 

T 

Triple? 

I 

0.277 

I     Q38 

3781.330 

T 

n.m. 

W2 

Many  comps.      n  diffuse      Not 

3786.092 

2 

Triple 

3 

0.220 

I.  "^ 

resolved 

3786.314 

2 

Triple? 

n.m.W2 

W2 

3786.820 
3788.046 

2 
4 

Unaffected 
Octuple 

3,3 

0.214  (4) 
0.108  (2) 
o.ooo  (i) 
o.ni  (2) 

O.  Ill    (2) 

o.ooo  (3) 

O.lOg   W 

1.491 

0-753 
o.ooo 

O    774. 

0.774 

o.ooo 
0.760 

Magnetic  duplicate  of  3743.508 

0.219  (4) 

3790.238 

2 

Sextuple? 

2 

O.  164  \V2 

W2 

I    142 

3794.485 

I 

Triple 

3 

o.  197 

3795.147 

1 

Septuple? 

2 

0.325 

W2 

2    2<C7 

3797.659 

^ 

Triple 

3 

0.261 

I    809 

Probably  3  p-comps. 

3798.655 

4 

Triple 

3 

0.326 

2    2<CO 

3799.693 

] 

Triple 

3 

0.326 

2    258 

3801.820 

I 

Quadruple? 

i 

0.190 

W2 

I    ^14 

3805.486 

3 

Triple 

3 

o.  204 

3806.865 

1 

Triple 

3 

0.226 

I     ^0 

3807.681 

3808.423 
3808.873 
3810.901 
3813.100 

3813-781 
3814.671 

2 

I 
I 
I 

4 

i 
I 

7  or  9 
comps. 

Quadruple? 
Triple 
Triple 
Septuple? 

Triple 
Quintuple 

2,2 

I 
2 

3 

2 

I 
1,1 

O.IlS  W3 

0.227 
0.288 
0.255 
o  .  203  Wi 

0.266 

? 

o.ooo  (2) 

0.182  (i) 

0.109  (i) 

o.ooo  (2) 

0.100  (i) 

W2 

W2 
Wl 

0.324 

0.814 
1-565 

1-737 
1-756 
1.396 

1.828 
? 
o.ooo 
1.250 

0.751 

0.000 

0.689 

2.226 

Sharp   inner   pair  of   «-comps. 
measured.   Wide  fringes  prob- 
ably indicate  2  outer  pairs 

«-comps.   fringed.     Probably  3 
p-comps. 

Faint.     Blend    makes  n-comp. 
difficult 

24  INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

TABLE  i. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON — Continued. 


i 

CHARACTER 

| 

A 

\ 

AX, 

'X2 

1 

SEPARATION. 

0 

1 

n-COMP. 

p-COVP. 

W-COMP. 

/>-COMP. 

Triple 

i  8n 

Sextuple? 

I 

O    258  W2 

W2 

I  .  772 

7QT>7     7«6 

Triple 

I     I  SO 

Difficult 

2«2O     C86 

Triple 

o  282 

I    O32 

Line   reverses    easily.     Comps. 

7821    728 

Triple 

o  218 

I    4,03 

never  very  sharp 

7821  081 

Triple 

I 

O    141 

o.o6c 

Triple 

I    2^8 

Not  given  by  Rowland  as  Fe. 

Triple 

Computed  X  =  3824  .  463 

g 

Septuple? 

W2 

I    872 

w-comps.  fringed.      Probably  3 

7827  080 

Triple 

I     C7C 

p-comps. 

7870  806 

Triple 

n  m. 

Faint 

Triple 

ci2 

7877  dc8 

Sextuple? 

716 

6 

Septuple? 

2 

o  248  Wi 

Ws 

687 

«-comps.  fringed.     Probably  3 

Triple 

o  266 

808 

p-comps. 

7877   768 

Quadruple? 

o  198 

Triple 

O    222 

<o6 

Triple? 

i 

o  257 

Wi 

748 

Enhanced  line,  diffuse 

3840.580 

4 

9  comps. 
Triple 

2,1 

2 

Pair  III,  0.337(1) 
Pair   II,  0.220  (2) 
Pair     I,  0.106  (4) 

0.061  (2) 
o.ooo  (3) 

0.059  (2) 

2.285 
1.492 

0.720 

I    112 

0.414 
0.000 

0.400 

Difficult.     Comps.  not  fully  re- 
solved 

Triple 

a 

o  220 

I    4OO 

3845.310 

I 

Sextuple? 
Triple 

2,2 

0.234  w3 

0.197 

1.582 
I    6?O 

1-332 

n-comps.  almost  resolved 
Enhanced  line 

Triple 

•2 

o  ?oo 

2    O2  7 

3850.118 
3850.962 

4 

2 

Unaffected 
Sextuple? 
Quadruple? 

2,3 
2 

0.298  ws 
o  268 

0.218 

Wl 

2.009 
i  801; 

1.470 

«-comps.  almost  resolved 

Triple 

Triple 

7 

O    24.3. 

I    6^2 

6 

Triple 

Triple 

O    3.22 

2  160 

3863  888 

Triple 

I 

O    2OI 

I    O4Q 

Very  faint.    Enhanced  line 

3865.674 

4 

Quintuple 

3.3 

0.172  (i) 

o  ooo  (2) 

0.340 

1.151 

O  OOO 

2-275 

o  171  (i) 

T      T^^ 

^867  «6 

2 

Triple 

7 

O.  77Q 

2.267 

Triple 

2 

o  406 

2    711 

3871-963 
3872.639 

I 

4 

Quadruple 
12  comps. 

2,2 

2,3 

0.272 
Pair  IV,  0.452  (i) 
Pair  III,  o  344  (2) 

0.125 
Pair  11,0.231  (6) 
Pair    I,  n.m.     (i) 

I.8I4 

3-013 
2    2Q3 

0.834 
1.540 

Enhanced  line 

Pair   II,  0.225  (2) 

i  .  <;oo 

Pair     I,  o  116  (i) 

0777 

Triple 

3878.152 
5878  720 

4 
e 

10  comps.? 
Triple 

2,3 

a 

0.311  w» 
o  2.46 

0.151  wi 

2.067 

2    3OO 

1.004 

Probably  6  n-,  4  />-comps. 

3883  426 

Triple 

?88?   6?7 

Sextuple? 

2 

O    234.  Wi 

Wl 

I     ^^O 

3886  ,-IA 

Triple 

3887-196 
3888.671 

3 
4 

Sextuple? 
ii  comps. 

2,2 
2,2 

0.335  W2 

0.190  (2) 
0.128(3) 
0.072  (3) 

o.ooo  (i) 
0.077  (3) 

0.117 
Pair   11,0.235 
Pair     I,  n.m. 

2.217 
1.256 
0.846 
0.476 

o.ooo 

0.509 

o  886 

0-774 
I.SS4 

Red  n-comps.  disturbed  by  blend 

I    2^6 

3888  971 

Triple 

3800  086 

Triple 

2 

o  «8 

3892.069 
3893-542 

i 

2 

Quadruple? 
Quadruple? 

2 

3 

0.237  wi 
0.269 

Wl 
Wi 

i  564 
1-775 

Red  n-comp.  stronger.     Violet 
£-comp.  stronger 

MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON. 
TABLE  i. — MEASUREMENTS  or  ZEEMAN  EFFECT  FOR  IRON — Continued. 


25 


f3 

CHARACTER 

= 

A 

X 

AX, 

'X2 

1 

M 

SEPARATION. 

o 
1 

tt-COMP. 

/>-COMP. 

M-COMP. 

p-COUP. 

Triple 

2    Oil 

?8nc   80  3 

Triple 

2    286 

Triple 

1.6^8 

3898  032 

Triple 

o  376 

2.474 

3898-231 

2 

Quadruple 
Triple 

2,2 

0.707 

O    340 

0-352 

4.653 

2.294 

2.317 

3903.090 
3904.052 

5 

i 

10  comps.? 
Sextuple? 
Triple 

2,2 
2,1 

0.278  Wa 
0-233  wl 

0.152  wi 
0.098 

1.825 
1-529 

0.998 
0.643 

Probably  6  n-,  4  ^-comps. 
Enhanced  line 

Triple 

2    273 

I    663 

Triple 

2.28o 

Difficult  blend  with  3909.802 

Triple 

o  326 

2.128 

Triple? 

2    O27 

3917.324 

3918.464 

3018  163 

2 

I 
I 

Septuple? 

Triple 
Triple 

2 
2 

Q.554W2 
n.m. 

O    333 

Wa 

3.6lO 
2.l69 



w-comps.    have     inner   fringes. 
Probably  4  n-,  3  />-comps. 

Triple 

O    17? 

I    130 

Triple 

2  .  271 

Triple 

2    28l 

Quadruple? 

Wi 

I  .046 

Triple 

2    43Q 

_ 

3028  071 

Triple 

O    312 

2.28l 

Triple 

2    282 

3O3O   41O 

4 

Triple 

7 

O    312 

2.270 

Quadruple? 

W2 

2    670 

3935.965 

i 
i 

Sextuple? 
Triple 

2,2 

0.319  Wi 

O.227 

2.059 
2  .477 

1-465 

Enhanced  line 

I 

Triple? 

Enhanced  line.     Diffuse 

Triple? 

2 

Wl 

2    062 

Triple 

I    77O 

3Q47    142 

Quadruple? 

I 

o  243  Wi 

W2 

i  .  t;6o 

Quadruple? 

Wl 

2    417 

?Q48  .  246 

Triple 

I 

o  247 

1.581; 

2 

Triple 

I     1OO 

3Q1O.  IO2 

2 

Triple 

7 

o  348 

2  .  230 

3QCI     in 

2 

Triple? 

2 

0    288  Wi 

Wl 

I  844 

3952-754 

I 
I 

Sextuple? 
Triple 

2,1 

2 

0.287  WI 

0.145 

1.837 

I  862 

0.927 

Red  p-comp.  twice  as  strong  as 
violet 

2 

Triple 

3oc6  810 

2 

Triple 

-2 

o  289 

I  846 

Triple 

I  807 

Comps.  hazy 

3963-252 

I 
I 

? 
Triple 

W3 

Wl 

2    672 

«-comps.  not  resolved 
Faint 

3966.  212 

2 

Septuple? 

2 

O-474  W2 

Wl 

3    OI3 

Measurement  is  for  wide  pair 

2066    778 

2 

Sextuple? 

2 

o  338  Wa 

W2 

2    147 

«-comps.    which    have    inner 
fringes,  ^-comps.  not  resolved, 
probably  triple 

3967  .  S7O 

7 

Triple 

3 

o.  198 

i.  258 

3968.114 
3969.413 

I 

5 

Triple? 

Septuple? 

2 

n.m. 
0.354  Wi 

Wi 
W| 

2  .  247 

Probably  4  n-,  3  />-comps. 

3Q7O.  14.O 

i 

Triple 

2 

o  348 

2    2O7 

•2Q7I    4.7C 

i 

Sextuple? 

2 

Wl 

3976.532 
3976.692 
3977.891 
3981.917 

3084  in 

i 
i 

2 
I 
2 

Triple? 
Triple 
Triple 
Sextuple? 
Triple 

I 
I 

3 

2,2 

•2 

o-33° 
0.319 
0.441 

0  .  24O  W2 

Wi 

0.127 

2.088 
2.019 
2.787 
1-513 

}  
0.800 

Difficult  blend 

3985-539 
3986.321 
3990.011 

3990-525 
3994.265 

I 
I 
I 
I 
I 

Triple 
Sextuple? 
Triple? 
Triple? 

Triple 

2 
2 
I 
2 
2 

0.282 
0.196  W2 

0.293  wi 

0.251 
0.283 

WS 
Wl 
Wl 

1.775 
1-234 
1.840 

1-577 
1-774 

26  INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

TABLE  i. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON — Continued. 


X 

INTENSITY.  1 

CHARACTER 

OF 
SEPARATION. 

WEIGHT. 

AX 

AX/X2 

REMARKS. 

H-COMP. 

p-coup. 

W-COMP. 

/>-COMP. 

3996.140 
3997.115 
3997.547 
3998  .  205 

4001.814 

4005.408 

4006  .  464 
4006.776 
4007.429 

4009  .  864 

4013.964 
4014.677 
4017.308 
4018.420 
4022.018 
4024.881 

4029.796 

4030  .  646 

4032.117 
4040.792 
4044  .  056 
4044  .  766 

4045.975 
4062.599 

4063  .  759 
4067.139 
4068.137 
4070.930 
4071.908 
4073.921 
4074.947 
4076.792 
4078.515 
4079.996 
4080  .  368 
4084  .  647 
4085  .  161 
4085  .  467 
4096  .129 

4098.335 
4100.901 
4107.649 
4I09.9S3 

4114.606 
4118.708 
4120.368 
4121.963 
4122-673 

4123.907 
4126.040 
.4126.344 
4126.798 
4127.767 
4130.196 

4132.235 

i 
i 
3 

2 

I 

6 

i 
i 
i 

2 

I 
2 

I 
I 
2 
I 
I 
I 
I 
I 
I 
I 

15 
2 
IO 

I 
I 
I 

8 

i 
i 

2 

I 
I 
I 
I 
I 
I 
I 
I 
I 
2 
2 

I 

3 

i 
i 
i 

4 

? 

Triple 
Triple 
Sextuple? 
Triple 
13  comps.? 

Triple? 
Triple 
Triple 
Septuple 

Triple? 
Triple 
Sextuple? 
Triple 
Sextuple? 
Triple? 
Quadruple? 
Sextuple? 
Triple 
Triple 
? 
Triple? 
Triple 
Sextuple? 
Triple 
Sextuple? 
Quadruple? 
Triple? 
Triple 
Triple 
Octuple? 
Triple 
Triple 
Triple 
Triple? 
Triple? 
Triple? 
Triple? 
Triple? 
Sextuple? 
Triple 
Triple 
Sextuple 

Sextuple? 
Triple 
Triple 
Triple? 
Quadruple? 

Triple? 
Triple? 
Triple? 
Triple 
Triple 
Triple 

13  comps.? 

i 
3 

2 

3 

2 

I 
I 
2 
2,2 

I 

3 

2 

I 
2 
I 
2 
2 
2 
2 

2 

3 

2,2 

3 

2,2 
2 
2 
2 
2 
2,2 
2 
2 
2 

2 

I 
I 
2 
2 

I 

3 

2,3 
2,2 

3 

2 

I 
I 
I 
I 

3 

2 

W3 
0.259 
O.266 

o.  226  wi 

0.415 

0.461  W3 

O.  211 

0.383 
0.176 

Pair   II,  0.470  (i) 
Pair     1,0.284(3) 

0.236  wi 
o.  250 
0.397  wi 
0.288 
0.272  wi 
o  .  209  wi 
0.311 
0.274  wi 

0.2II 
0.254 

n.m.  Wz 
0.319 
0.298 

0.418  W2 
0.269 
O.4O2  W2 
O.4l8 
0.366 
O.I7O 
0.360 

0.302  Wa 
0.386 
0.184 
0.479 
n.m. 
0.300 
0.311 
0.400 
0.237 
0.383  wj 
0.302 

0-397 
Pair   11,0.382  (i) 
Pair     I,o.i88(i) 
0.376  wi 
0.271 
0.244 
n.m. 
n.m. 

0.402  Wi 
0.370 

0-335 
0.284 
0.196 
n.m. 

0.510  ws 

W2 

w-comp.  not  resolved 
Faint 

Measurement  is  for  outer  pair 
«-comps.     Wide  inner  fringes, 
probably  at   least  8  «-comps. 
and     5    p-comps.       Compare 
4132.235 
Blend 

Very  faint 
K-comps.  scarcely  resolved 

Comps.  diffuse 

Probably  6  H-comps. 

Very  faint 

Blend  makes  measurement  dif- 
ficult 

Faint 

»-comps.  hardly  separated,   p- 
comps.  almost  resolved 
Comps.  faint  and  diffuse 

Blend  makes  measurement  dif- 
ficult 

Faint,  »-comps.   rather  widely 
separated 
Measurement   is   for   outer   «- 
comps.  Wide  inner  fringes,  indi- 
cating4pairs.  5  p-comps.  almost 
resolved.     Similar  to  4005  .  408 

I.62I 
1.664 
1.414 
2.591 
2.874 

i-3i5\ 

2-385! 
1.096 
2.923 
1.766 

Wi 

W3 
Wi 

0.085  (i) 
o.ooo  (2) 
0.089  (i) 

Wl 

0.529 
O.OOO 

0.553 

1.465 
i-SSi 
2.460 
1.784 
.681 
.290 

•915 
.685 
.298 
•555 

W2 

Wl 
Wi 
Wi 
Wl 

W3 
Wi 

•950 
.820 
2.532 
1.628 
2.430 

2.525 
2.208 
1.025 
2.169 
1.819 
2.322 
1.106 
2.877 

0.588 
1.143 

0.097 

0.189 

W2 
Wl 

0.149 

0.897 

Wi 

Wl 
W2 

W2 
Wl 
W2 

1.798) 
1.864 
2-397J 
1.413 
2.281 
1.796 
2-352 
2.261 
1.113 

2.  22O 

1-597 
1.437 

O.I9I 

1.131 

0.797 

0.135 

W2 
W2 

W2 
W2 
Wi 

Wi 
W3 

2.364 

2-173) 
1.968 
i.667J 
1.150 

2.987 

MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON. 
TABLE  i. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON — Continued. 


\ 

!H 
H 
Dl 

CHARACTER 

JJ 

£ 

X 

AX 

A2 

I 

3 

SEPARATION. 

1 

M-COMP. 

p-COilf. 

W-COMP. 

p-COMP. 

4133.062 

2 

Sextuple? 

2 

0.273  wi 

Wl 

1.598 

4134.840 

2 

Sextuple? 

2 

0.303  w, 

wl 

I    772 

4136.678 

I 

Triple? 

2 

o.  252 

w, 

I  .472 

4137.156 

I 

Triple 

2 

0.314 

1.814 

4140.089 

T 

Triple 

n.m. 

Very  faint 

4142.025 
4143-572 
4144.038 

4147  836 

I 

3 
5 

i 

Triple? 
Quadruple? 
Septuple? 

Sextuple? 

2 
2 
2 

2 

0.392  w, 
0.280 

0-393  Wi 
O.34O  W2 

V/i 
Wi 

W2 

Ws 

2.285 

1.630 
2.288 

1.976 

n-comps.    have    inner     fringes. 
Probably  3  />-comps. 
Diffuse  ^-comp.  appears  stronger 

4149.533 

i 

Triple? 

2 

0.397  Wi 

w, 

2.305 

on  violet  side.    Possibly  blend 

4154.071 

2 

Triple 

I 

O.  37O 

2    196 

4154.667 

2 

Triple 

2 

O-379 

2    ICK 

4154.976 

2 

Triple 

I 

0.385 

2  .  2^O 

4156.970 
4157.948 

2 

I 

Sextuple? 
Sextuple? 

2,2 
2 

0.367  wi 

0.415  W2 

O.I2I 

W2 

2.123 
2  .400 

0.700 

4158.959 

4171  .068 
4172.296 

I 
I 
I 

? 

Sextuple? 
Triple 

I 

2,2 
2 

0.589  Wi 
o  .  390  w2 

0.315 

W3 
O.II7 

3-405 
2.242 
I.SlO 

0.672 

p-comp.  very  diffuse 

4172.923 
4173.480 

4173.624 

I 
I 

I 

In  pie 
Quadruple 

Triple 

1,1 

n.m. 

0.470 

n.m. 

0.185 

2.698 

I  .062 

Blend    with    next    line    makes 
measurement  difficult 

4175.082 

I 

Triple? 

2 

0.374 

Wi 

2    146 

4175.806 

2 

Triple 

2 

o.  206 

I    6o7 

4176.739 

I 

Triple 

j 

0.420 

2   4O7 

4179.025 

I 

V/3 

W2 

Comps.    very   diffuse,    not   re- 

4181.919 

4 

Triple 

3 

o.  339 

I    CMS 

solved.    Enhanced  line 

4182.548 

i 

Quadruple? 

I 

0.272  wi 

w 

I  .  ccc 

Faint 

4185.058 

2 

Triple 

3 

0.390 

2    227 

4187.204 

4 

Septuple? 

2 

0.395  wi 

W2 

2  .  2<;3 

tt-comps.  fringed.      Probably  3 

4187.943 

4 

Triple 

3 

0.402 

^-comps. 

4191-595 

3 

Septuple 

2,2 

Pair   II,  0.540  (i) 
Pair     I,  0.264  (4) 

0-135   (0 

o.ooo  (2) 
o.  143  (i) 

3.073 

1.502 

0.768 
O.OOO 

o  813 

4195.492 

i 

Triple 

2 

0.320 

i  818 

4196.372 

i 

Triple 

I 

O.  35Q 

4198.494 

1 

Triple 

3 

0.383 

2    172 

4199.267 

s 

Triple 

3 

o.  276 

i   $6< 

4200.148 

i 

Sextuple? 

i 

o  .  364  Wa 

W3 

2    062 

Faint  and  diffuse 

4201.089 

i 

Triple 

i 

0.438 

2    d.82 

Faint 

4202.198 
4204.101 

6 

i 

10  comps.? 
Triple 

2,2 

3 

0.323  w3 
0.373 

0.147  wi 

1.829 

2    I  IO 

0.832 

Probably  6  »-,  4  p-comps. 

4206.862 

T 

Triple 

I 

0.338 

4207.291 

I 

Triple 

I 

0.317 

I    7OI 

Faint 

4208.766 

I 

Quadruple? 

I 

0.413 

Wi 

2    332 

Faint 

4210.494 

3 

Triple 

3 

0.806 

4.  ^4.7 

4210.561 

I 

Triple 

i 

0.411 

2    3IO 

Enhanced  line  Fe?    Not  identi- 

4213.812 

I 

Triple 

2 

0.392 

2    2O7 

fied  by  Rowland 

4216.351 
4217.720 

I 
I 

Sextuple? 
Sextuple? 

2,2 
I 

0.457  W2 

0.402  w> 

0.236 

W3 

2.S7I 

2  .  2?O 

1.328 

Comps.  very  diffuse 

4219.516 

4220.509 

4222.382 

3 

i 

2 

Triple 
Triple 
Triple 

3 

2 
1 

0.284 
0.368 

0.475 

1-594 
2.066 
2  66s 

4224-337 
4225.619 

4226.116 

I 
I 
I 

Sextuple? 
Sextuple? 
Triple 

I 
2 

0-439  wi 
0.448  wi 
n.m. 

Wi 
W2 

2.460 
2.508 

4226.584 
4227.606 
4233-328 
4233-772 

I 

4 

2 
2 

Triple? 
Triple 
Sextuple? 
9  comps. 

I 
2 
2 
2,2 

0.381 
0.309 
0.282  Wi 
Pair  III,  0.780  (i) 
Pair    II,  0.550  (2) 
Pair     I,  0.265  (s) 

W2 

W2 
0.140  (2) 

o.ooo  (3) 
0.140  (2) 

2-133 
1.728 

1-574 
4.3SI 
3-068 
1.478 

0.780 

o.ooo 
0.780 

Enhanced  line 

28 


INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 


TABLE  i. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON — Continued. 


e 

7 

CHARACTER 

tj 

d 

X 

AX 

A2 

& 

SEPARATION. 

I 

n-COMP. 

^-COMP. 

»-COMP. 

p-cottr. 

42?6    112 

n 

Triple 

•2 

O  4?2 

2    SIO 

4238.970 

I 

Triple 

2 

O.32O 

1.781 

424O   OI4 

T 

Triple 

2 

o  440 

2    44.7 

4245    422 

T 

Triple 

3 

O.402, 

2  .  736 

4246.  251 

T 

Triple 

I 

0.273 

1  .514 

4.247    "COT 

I 

Triple 

2 

o  2c6 

I    Q73 

4248.384 

I 

Triple 

2 

o.  377 

2.089 

42  CO    287 

8 

Septuple? 

2 

2    11$ 

w-comps.  fringed.     Probably  3 

4250-945 
4260  640 

9 

TO 

12  comps.? 
Triple 

2,2 
2 

o  .  246  Ws 

O   423 

0.21  I  Wl 

1.361 

2    33O 

1.168 

/>-comps 
Probably  8  «-,  4  p-comps. 

4267.  122 

T 

Triple 

J 

o.  2,00 

I  648 

4267.985 

T 

Triple 

I 

0.528 

2.800 

4268.OI  1 

T 

Triple? 

I 

o  462 

Wj 

2    C3C 

4271  .325 

0 

Triple 

3 

O.  3Q4 

2  160 

4271  .934 

TO 

Triple 

3 

0.341 

1.868 

4282  .  <6i 

T 

Septuple? 

2 

O    3IO  W2 

Ws 

i  601 

»-comps.  fringed.      Probably  3 

4285.605 

T 

Triple 

3 

o  31  c 

I    7I"\ 

/•-comps. 

4294.301 
4298.  195 

5 
i 

Sextuple? 
Triple? 

2,2 
2 

0.319  w2 
0.457 

0.138 

Wi 

1.730 

2.474 

0.748 

»-comps.  almost  resolved 

4299  410 

5 

Triple 

3 

o  406 

2    IO7 

4302.353 

T 

Triple 

2 

0.316 

1  .  707 

Enhanced  line 

43°3-337 
4305.614 

I 
T 

Sextuple? 
Quadruple? 

2,2 

I 

0.415  w2 
0.328  Wi 

0.265 

Ws 

2.241 
I    76o 

I-43I 

Enhanced  line 

4308.081 

IS 

Triple 

3 

o.  320 

I  .  724 

4309.  541 

T 

Triple 

2 

O    32< 

I    7^0 

4315.262 
4325.939 

3 

TS 

Sextuple? 
Triple 

3,3 
3 

0.517  wi 
o.  245 

0.090 

2-777 
1  .  3OQ 

0.483 

4327  .  274 

T 

Triple 

2 

O    31  3 

I    6?2 

4328.080 

T 

Triple 

2 

o  246 

1  .  317 

4337-216 
4346.725 

2 

T 

Sextuple? 
Triple? 

2,3 

I 

0  .  264  W2 
O    2O2 

0.154 

Wj? 

1.404 
I     $4.$ 

0.819 

Blend  with  air  lines 

435I-930 
4352.908 

I 
2 

Septuple? 
Septuple? 

I 
2,3 

0.3II  W2 
O.4l6  W2 

W2 

0.075  (i) 

o  ooo  (2) 

1.642 
2.195 

0.396 
o  ooo 

Probably  3  p-comps.     May  be 
O,  but  given  by  Lockyer  as  en- 
hanced line  Fe 
»-comps.  fringed 

0.075  (*) 

o.  2,06 

4367.  749 

T 

Triple 

2 

O    311 

I    63O 

4369.941 

7. 

Triple 

3 

o.  282 

I    477 

4376.  107 

? 

Triple 

2 

4383.720 

?.n 

Triple 

3 

O    332 

I    727 

4385.548 
4388.057 

i 
I 

Quadruple 
Triple 

2,2 

0.367 

n.m. 

0.391 

1.910 

2.032 

Enhanced  line 
»-comps.  blended  with  adjacent 

4388.571 

T 

Triple 

2 

O   432 

2    243 

lines 

4391.123 

T 

Triple 

n.m. 

Faint 

4404.927 

T5 

Triple 

3 

0.334 

I  .  72O 

4407.871 

T 

Triple? 

2 

o  631 

Wi 

3247 

4408.582 

T 

Triple? 

2 

0.488 

Wi 

2  <;ii 

44I5-293 
4422.741 

IO 

I 

Septuple? 
Sextuple 

2 
2,3 

0.338  wj 

Pair    11,0.432  (i) 
Pair     I.  o  i  <C4  (i  ) 

Wj 

0.280 

1-734 

2.208 
o  787 

1-431 

K-comps.    have    inner    fringes. 
Probably  3  p-comps. 

\\i1  ^f~-> 

3 

Triple 

3 

0.42,0 

2  .  IO4 

4430  .  785 

I 

Triple 

2 

O    7IO 

3    662 

4433  .  390 

T 

Triple? 

n.m.  Wi 

W2 

Comps.  diffuse  and  blended  with 

4442.510 

4443-365 
4447.892 

4454-552 
4459-301 
4461.818 
4466.727 

2 
2 

2 

I 
2 
I 
2 

10  comps.? 
Triple 
Sextuple 

Sextuple? 
Sextuple? 
Triple 
Sextuple? 

2,2 
2 
2,3 

2,2 
2,2 

3 
2 

0.485  w3 
0.170 
Pair    II,  0.721  (i) 
Pair     I,  0.449  (i) 

0.445  Wl 

o  .  449  w2 
Q-435 
0.343  wi 

0.184  wl 

0.307 
0.173 

0.127 

Wi 

2.458 

0.861 

3-644 
2.269 

2-243 

2.258 
2.185 
1.719 

0.932 
1-552 

0.872 
0.639 

air  band 
Probably  6  «-,  4  p-comps. 

Close  to  air  line 

MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON. 
TABLE  i. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON — Continued. 


29 


\ 

1 

CHARACTER 

a 

A 

\ 

AX 

/X2 

& 

SEPARATION. 

9 

N 

tt-COMP. 

p-COMP. 

n-coMP. 

p-cour. 

4.4.6o    ^4  ^ 

i 

Triple? 

2 

O   4^8  Wi 

Wi 

2    IO2 

4.4.76  18s; 

2 

Septuple? 

2 

I    ?27 

w-comps.  fringed      Probably    3 

4482.338 
4482.438 

ddSd    ^02 

I 
2 

I 

Sextuple? 
Quadruple? 

Sextuple? 

I.1 
I.I 

2 

0.401  Wi 

0.139 

0.146 

0.229 

1.996 
O.692 

0.727 
i  .  140 

p-  comps. 
w-comps.  very  diffuse 
Probablyalso  outer  pair«-comps. 
Close  blend  with  preceding 

4489.351 

I 

Triple 

Enhanced  line 

4491  .570 

I 

Triple? 

w 

»-comps.    close,    not    resolved. 

4494  •  738 

2 

Septuple? 

2 

i  40  1; 

Enhanced  line 
w-comps.  fringed.      Probably  3 

4508.455 

T 

Triple 

I 

o  184 

o  QOI 

^-comps. 
Enhanced  line.    Comps.  diffuse 

4  <;i  5   508 

I 

Triple 

2 

I  628 

Enhanced  line 

I 

Triple 

2 

4522.802 
452S-3I4 
4528.798 

I 
I 

3 

Triple 

Sextuple? 
Septuple? 

2 

1,2 
2 

0.274 

0.457  W2 

o  3<c8  ws 

0.164 

1-339 

2.232 

I    74^ 

0.801 

Enhanced  line 
w-comps.  fringed.      Probably  3 

4531.327 
4548.024 

i 
i 

Sextuple? 
Triple 

2.2 

0.398  Wi 

o.  104 

•939 

er>4 

0.506 

p-comps. 

4549.642 

i 

Triple 

O    3IO 

.  ^41 

Enhanced  line 

4556.063 

T 

Triple 

I 

408 

Blend  with  4556  306.  Enhanced 

4556.306 
4584.018 

I 
1 

Triple? 
Triple 

2 

n.m. 
o  ^76 

Wi 

78o 

line 

4592.840 
4603  .  1  26 

I 
T 

Sextuple? 
Sextuple? 

2,2 
2 

0.416  Wi 

0.126 

.972 
2    671 

0-597 

4611  .469 

I 

Triple 

2 

0.652 

3.OO7 

4619.468 

Quadruple? 

2 

2    723 

4629.521 

I 

Triple 

2 

o  308 

i  8<7 

Very  close  to  air  line.    Enhanced 

4637.685 

I 

Triple? 

n.m. 

Wi 

line 
K-comps.  diffuse.  Close  to  air  line 

4638.193 

T 

Triple 

n.m. 

4647.617 

T 

Triple 

2 

O.  3Q2 

1.8l4 

4654  .  800 

I 

Triple? 

I 

o  <;43  Wi 

2    "CO6 

n-  and  ^-comps.  diffuse 

4667.626 

I 

Triple 

2 

o  481 

2    2O7 

4668.331 

I 

Sextuple? 

O    362  Wa 

i  661 

4679.027 

I 

Triple 

2 

2    124. 

4691.602 

I 

Triple 

2 

o  «8 

.626 

4707.457 

T 

Triple? 

2 

o  36^ 

647 

4710.471 

T 

Triple 

I 

o.  242 

.OQI 

Blend  with  air  line 

4736.031 

I 

Triple? 

I 

O  4O<  Wi 

8o< 

Weak,  rather  diffuse 

4736.963 

I 

Sextuple? 

2 

808 

4741.718 

T 

Triple 

n  m 

Faint 

4745.992 

T 

Triple? 

Comps.  weak  and  diffuse 

4787.003 

I 

Triple 

2 

o  400 

i  78? 

4788.952 

T 

Triple? 

n  m 

w-comps.  diffuse 

4789.849 

T 

Sextuple? 

4839.734 
4859.928 

I 
1 

Triple 
Octuple 

2,2 

n.m. 
n.m. 

Too  weak  to  measure 
Strong  central  w-comp.   Trace  of 

0.275  (0 

o.ooo  (4) 

0.289  (0 

n.m 

0.271  (2) 

o.ooo  (3) 
0.269  (2) 

1.166 

o.ooo 

1.222 

1.147 
o.ooo 

1-139 

faint  outer  pair 

4871.512 

4872-332 
4878.407 
4890.948 

3 

2 
I 
3 

ii  comps.? 

Sextuple 
Triple 
10  comps.? 

1,2 

2,3 
3 

2,2 

0.336  w2 

Pair   II,  1.044  (3) 
Pair     1,0.515  (2) 
1.092 

0.635  W3 

0-193  (i) 
0.093  (2) 

o.ooo  (3) 

0.087  (2) 

0.181  (i) 

0.538 
0.341 

I.4I4 

4.400 
2.I7I 

4-574 
2.656 

0.813 
0.392 

o.ooo 
0.366 
0.762 
2.264 

1.424 

»-comps.  fringed.      Probably  3 
pairs 

Violet  comp.  3/2  stronger  than 
red 
K-comps.     uniformly    widened, 
probably  3  pairs.    Trace  of  in- 
ner pair  />-comps. 

30          INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

TABLE  i. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON — Continued. 


g 

55 

CHARACTER 

| 

A 

X 

AX 

/X2 

1 

SEPARATION. 

o 
3 
£ 

M-COMP. 

p-COMP. 

W-COMP. 

p-COtlf. 

4801  68? 

? 

2 

O    388  W2 

i  620 

M-comps.  fringed.      Probably  3 

4903.502 

4.OII  .06^ 

i 

i 

Sextuple? 
Triple 

2,1 
2 

0.866  wi 

0.152 

3.600 
i  .644 

0.632 

p-comps. 

4919.174 
4020.68? 

5 

8 

Sextuple? 
Triple? 

2,2 
2 

0.591  w3 

0.270 

2.441 
i  841; 

I.H5 

Probably  complex,  but  widening 

4924    107 

2 

2     C77 

may  be  due  to  strength 
H-comps.  fringed.    At  least  3  p- 

4024    Qt;6 

comps.     Enhanced  line 
Comps.  weak  and  diffuse 

4038.  O07 

Quadruple? 

2 

^    O23 

4939  .  868 

Triple 

2 

o  <8o 

2.378 

4946  .  568 

Triple 

2 

o  481 

1.968 

4957.480 

4017    ?8<; 

Sextuple? 
Triple? 

2,2 

o  .  630  wi 

O.IQO 

2-565 

2    3O7 

0-773 

Widening  may  be  due  to  strength 

4966.  270 

Triple 

2 

o  588 

2     H4. 

AQ-7-1     28l 

4078  78  s 

Unaffected? 

Only    narrow    H-comp.   visible. 

4982  682 

Triple? 

I    8OO 

Faintness  of  line  may  prevent 
appearance  of  others.  Possibly 
similar  to  4859.928 

408  3  .  4  *  ? 

Triple 

o  <8? 

2    ?62 

Blend  with  adjacent  lines 

4984.028 

Quadruple? 

2 

Wj 

2    2OQ 

4985.432 

Triple 

2 

O    4?2 

3.337 

4985  .  730 

Sextuple? 

2  88? 

40OI    4^2 

Triple? 

Faint 

4994.316 

Triple 

2 

0    <&l 

2  .332 

5OO2  .  044 

Triple 

2 

I    660 

Close  to  air  line 

5005  .  896 

Triple 

I 

1  .Q?3 

w-comps.   blend  with    adjacent 

5006.306 
<OI2  .  212 

Sextuple? 
Triple 

2 

0.295  wi 

0.182 

I.I76 

2     I  *6 

0.724 

line 

5015.123 

Quadruple? 

2 

I  488 

coi8  620 

Enhanced  line 

5022.414 

i 

Triple 

2 

o  263 

1  ,043 

5027.305 

i 

Triple? 

I 

Wj? 

I  008 

Diffuse  comps.  due  to  blend  with 

5028.308 

Triple 

2 

i  "?o6 

5027.939 

co?o  428 

Triple 

5041  .  255 

Triple 

Wi  ? 

I    O'sO 

Widening  of  p-comp.  probably 

5041  .  936 

Triple? 

2    O^4 

due  to  blend  with  5041  .069 

5050  .  008 

Triple? 

a 

Wi 

I    72^ 

5051  .825 

Triple 

a 

O    ?2I 

2  .042 

5065.207 

Triple? 

I     3  2O 

Comps.    diffuse,    disturbed    by 

5068  .  944 

Triple 

3 

0.684 

2.664 

blend 

5074.932 

Sextuple? 

2 

Wj 

i   «8? 

5079  .  409 

I    771 

Blend  with  adjacent  lines.  Prob- 

5079.921 

i 

Septuple? 

i,i 

0-737 

0.206  (i) 

2.856 

0.798 
o  ooo 

ably  at  least  7-comps. 
Faint.    Probably    weak     inner 
pair  w-  comps. 

O    2IO  (i) 

0.814 

5083.518 

T 

Triple 

2 

0.4,71; 

1.840 

5090.954 

T 

Sextuple? 

Comps.  weak  and  diffuse 

S097.I7S 
5098.885 
5107.619 
5107-823 
5110.574 

5123.899 
5125.300 
5I27.533 

Sextuple? 
Quadruple? 
Triple 
Sextuple? 
Quadruple 

Unaffected 
Sextuple? 
Triple 

2 
2 
I 
I 
1,1 

2 
2 

0.513  wi 
0.607 
0.404 
0.625  wi 

0.539 

0.519  wi 
0.676 

W2 
Wj 

Wj 
0.226 

Wj 

1-974 
2-333 
1-5491 
2-394* 
2.066 

1.976 
2.572 

0.866 

Blend 

Measurement  difficult  owing  to 
blend  with  5109.827 

5131-642 
5I33-870 

Triple 
Sextuple? 

2 
2 

0.957 

0.459  wi 

Wi 

3-634 
1-743 



Very  faint 
p-comp.  almost  resolved 

MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON. 
TABLE  i. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON — Continued. 


>H 

H 

5 

CHARACTER 

| 

2 

kft 

A; 

tft 

a 

H 

X 
h-t 

SEPARATION. 

o 

I 

W-COMP. 

p-COMP. 

B-COMP. 

/i-COMP 

5137.558 

Sextuple? 

2 

0.567  wi 

Wa 

2.148 

5139-427 

Triple? 

2 

0.716 

Wl 

2.713) 

Close  blend  makes  judgment  of 

5139.644 

5143  .III 

Quadruple? 
Triple? 

2 

i       I 

0.693 

0.578 

W2 

Wi 

2.622) 

2    184 

^-comps.  difficult 
Blend  with  adjacent  lines 

5151  .020 

Quadruple? 

I 

2' 
0.629  Wi 

W2 

2.371 

Very  faint 

5152.087 

T 

Octuple? 

n.m. 

n.m. 

Probably  5  n-,  3  ^-comps     Very 

5159.231 

T 

Triple? 

I 

0.442  W2 

W2 

1.662 

faint 
Comps.  very  diffuse 

5162  .449 

T 

Triple? 

2 

0.586 

W2 

2  .  2OO 

5167.678 

8 

Triple 

2 

0.462 

I  .730 

5169.220 

in 

7  or  9 

2 

0.563  W2 

Wa 

2.IO6 

Enhanced  line.  «-comps  fringed 

5171.778  . 

T 

comps.? 
Triple 

3 

o.  521 

I  -949 

and  probably  compound,     p- 
comp.    much    widened    with 
strong    center.      Blend    with 
5169.069. 

5191.629 

T 

Septuple? 

2 

O  .  7O2  W2 

W3 

2.6o6 

»-comps.  fringed.      Probably  3 

5192-523 

5195.113 

I 

T 

Sextuple? 
Triple 

2,2 

3 

0.749  wi 

0.457 

0.213 

2.780 
1.695 

0.790 

p-comps. 

5195.647 

T 

Quadruple? 

n.m. 

Comps.  very  diffuse 

5197.743 

Triple 

2 

0.304 

I.I25 

Enhanced  line 

5198.888 

Quadruple? 

n.m. 

W2 

Comps.  very  diffuse 

5202.516 

Triple 

3 

0.683 

2.525 

5208.776 

Triple? 

2 

0.623 

Wl 

2.294 

5215.353 

Triple? 

2 

0.62*; 

2.296 

5216.437 

Triple 

2 

0.305 

I.  I  2O 

5217.552 

Triple? 

2 

0.611; 

2.259 

5225.695 

Quadruple? 

n.m. 

n.m. 

Very  faint,  p-comp.  apparently 

5227.043 

5227.362 

I 

5 

Sextuple? 
Triple 

2,2 

3 

0.949  Wa 
O.4I  T. 

0.281 

3-472 
I.5I2 

1.030 

wide  doublet 
Probably  4  «-comps. 

5230.030 

T 

Triple? 

2 

o.6ic 

2.248 

5233.122 

5 

Septuple? 

2 

O  .  507  W2 

Wa 

1.851 

«-comps.  fringed.     Probably  3 

5234.791 

T 

Triple 

2 

0.385 

2.147 

p-comps. 
Enhanced  line 

5242.658 

T 

Triple 

2 

0.385 

I  .400 

5250.817 

Triple? 

2 

o  618 

2.  243 

5263.486 

T 

Triple 

2 

o.6t;i 

2.352 

5266.738 

3 

7  or  9 

2 

O    5O2  W3 

I.SlO 

ft-comps.  widely  fringed.    Prob- 

5269.723 

R 

comps? 
Triple? 

3 

o.  =;oi 

Wi 

1.804 

ably  3  p-comps. 

5270.558 

5 

Triple 

2 

1.076 

5273.339 

T 

Triple 

2 

0.651 

2.343 

5276.169 

T 

Sextuple? 

I 

O    431   W2 

I  .547 

Enhanced  line 

5281.971 
5283.802 

2 

3 

? 
Triple 

I 

•2 

0.311  w3 
o  62? 

Wj 

i.  US 

2.232 

n-comps.  strongly  fringed.  Prob- 
ably 5  ^-comps. 

5302.480 

?. 

Triple 

3 

0.632 

2.272 

5316  .  790 

4 

Triple? 

2 

O   4.^  Wi 

1  .610 

Enhanced  line.    Diffuse  comps 

5324.373 

S 

Triple 

•2 

o  648 

2.286 

may  be  due   to  character  of 
line 
Red  comp.  slightly  stronger  than 

5328.236 

7 

Septuple? 

2 

o  470  Wi 

Wa 

1.656 

violet 
K-comps.  fringed       Probably  3 

5328.696 
5340.121 
5341.213 

5353-571 
5365-069 
5365.596 
5367.669 
5370.166 
5371-734 

3 

2 

3 

i 
I 
i 
i 

2 

6 

Sextuple? 
Triple 

Triple 
Sextuple? 
Triple 
Triple? 
Triple? 
9  comps.? 

2,2 
2 
1,2 

I 
I 
2 
2 
2 

0.488  W2 
0.664 
0.486  W3 

n.m. 
0.354  w2 
0.471 
0.414 
0.456 
0.413  w2 

0-275 
0.429 

W2 

Wi 
Wl 
W2 

1.718 
2.329 
1-703 

1.229 

1.636 

1-437 
1-581 
I-43I 

0.968 
1.502 

p-comps. 

»-comps.    blurred,  probably  at 
least  6 
Very  faint 
oomps.  very  diffuse 
Blend  with  preceding  line 
Diffuse 
Diffuse 
»-comps.  fringed.      Probably  6 
»-,  3  ^-comps. 

32          INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

TABLE  i.— MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON — Continued. 


1 

CHARACTER 

| 

A 

\ 

AX 

/x2 

1 

SEPARATION. 

o 

i 
* 

«-COMP. 

p-COlfP. 

n-coitp. 

p-COMP. 

^783    <78 

Triple? 

2 

Wi 

i  6<;6 

C7Q3  .  37C 

3 

Triple 

2 

o  673 

2    7T4. 

5397-344 
S404-3S7 
5405  989 

6 
6 

Sextuple? 
Triple? 
9  comps.? 

2-3 
2 

2,2 

0  .  630  W2 

0.467  wi 
Pair    II,  0.461  (i) 
Pair     I,  0.222  (4) 

O.222 
Wi 
O.II7  (2) 

o.ooo  (3) 

O    121  (2) 

2.l6.3 

1-599 
1-577 
0.760 

0.762 

0.400 
0.000 

o  414 

Diffuse 
Probably   third    pair   n-comps. 
outside 

5411  .  124 

7 

Triple? 

2 

O   43?  Wi 

i  486 

Diffuse 

5415.416 

C 

Triple? 

2 

o  510  Wi 

Wi 

I    73O 

Diffuse 

5424.290 

5 

Triple? 

2 

o  .  498  Wi 

Wi 

I  -603 

Diffuse 

5429.911 

5434.740 
5445  .  259 

6 

5 

2 

10  comps.? 

Unaffected 
Triple? 

2,3 

2 

0.607  w» 
o  415 

0.300 
Wi 

2.059 
I     3QO 

1.017 

3  or  possibly  4  pairs  n-comps. 
Probably  weak  inner   pair  />- 
comps. 
Diffuse 

5447.130 

5 

12  comps. 

2,3 

Pair  IV,  0.874  (0 
Pair  III,  0.701  (2) 
Pair   II,  0.477  (2) 

Pair   II,  0.447  (6) 
Pair     I,  0.226  (i) 

2.946 

2.363 
I  608 

1-507 
0.762 

«-comps.  barely  resolved 

Pair     I,  0.219  C1) 

0.738 

5455.834 

4 

Quintuple 

2,3 

0-347  (i) 
o.ooo  (2) 

0.680 

If 

1.163 
o  ooo 

2.283 

Central   line  of   »  triplet  dis- 
placed   0.009  A    toward    red 

0.345  (i) 

i  .  160 

from  no-field  line 

5463  .  494 

Triple 

I 

o  ^6s 

i  8q? 

Very  faint 

5474.113 

Triple 

I 

0.686 

2.280 

Very  faint 

5476.500 

Triple 

n.m. 

5476.778 

Triple 

2 

0.647 

2.1*7 

5487.959 

Quadruple? 

n.m. 

Very  faint 

5497-735 

3 

Octuple 

2,2 

0.683  (4) 
0.352  (2) 
o.ooo  (i) 
o  34°  (2) 

0.346  (2) 
o.ooo  (3) 
0.341  (2) 

2.260 
1.165 

0.000 

I    127 

1.  144 

o.ooo 
1.128 

0.706  (4) 

2    «8 

5501.683 

3 

Sextuple? 

2 

I    OOI  Wj 

3    3O7 

Appears  as  diffuse  triplet.     All 

5507.000 

3 

9  comps.? 

2 

J'.5W 
3   38? 

comps.  doubtless  compound 
Probably  6  «-,  3  p-comps.  Outer 

5535.644 

i 

Triple 

J 

I    4.27 

w-comps.  strongest 
Blend  with  air  line 

5555.122 

i 

Sextuple? 

I 

o  502  wi 

I    628 

Weak  and  diffuse 

5563.824 

T 

Triple 

2 

O.6<C2 

2  .  IO7 

Faint 

51565.931 

T 

Sextuple? 

I 

I     <C42 

Comps.  diffuse 

$569  .  848 

1 

Septuple? 

2 

O    33C  Ws 

I    080 

w-comps.  fringed.      At  least  3 

5573.075 

3 

Septuple? 

2 

I     "III 

#-comps. 
n-comps.  fringed.      At  least  3 

5576-320 
5586.991 

i 
5 

Unaffected 
Septuple? 

2 

o  510  Wj 

W2 

I    634 

p-comps. 
n-comps.  fringed.     Probably  3 

5598.524 

T 

Triple 

n.m. 

close  p-comps. 
Very  faint 

5603.186 

I 

Quintiple 

2,2 

0.372  (i) 
o  ooo  (2) 

0.728 

1.186 

O   OOO 

2.318 

Compare  5455.834 

O    34.3  (i) 

1  .002 

5615.877 

6 

Triple 

2 

0.586 

i-8<!Q 

5624.769 
5638.488 

i 
i 

Sextuple? 
Sextuple? 

1,2 

0  .  664  W2 

n.m.  W2 

0.481 
W2 

2.098 

1.520 

Faint  and  diffuse 

5659.052 
5662.744 
5693-865 

i 
i 
4 

Sextuple? 
Triple? 
Triple 

2,2 
2 

0.724  wi 
0.596 
n.m. 

0.307  Wi 

Wi 

2.259 
1.858 

0.960 

n-comps.  diffuse 
Faint 
Very  faint 

5701.772 
5706.215 
5709.601 
5718.055 

5731.984 
5752.254 

I 
i 
i 
i 
i 

Triple 
Triple? 
Quadruple? 
Triple 
Sextuple? 
Sextuple? 

2 
2 
2 
2 

I 

0.607 
0.605  wj 
0.785  wi 

0-383 
0.631  Wi 

Wl 
Wj 

W2 
Wa 

1.867 
1.858 
2.408 
1.172 

1.920 

p-comp.  almost  resolved 

Comps.  diffuse 
Comps.  diffuse 

5753-344 
5763.218 

5775.304 
5816.601 

Triple 
Triple 
Sextuple? 

2 

3 

I 
I 

0-575 
0.631 
0.762  wi 
0.442  wj 

Wi 

Wj 

1-737 
1.900 
2.279 
1.306 

Comps.  diffuse 
Probably    numerous    H-comps. 
Very  diffuse 

MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON. 
TABLE  i. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON — Continued. 


33 


x 

E 

•n 

CHARACTER 

H 
i 

i 

\\ 

A; 

vw 

H 
K 
^H 

SEPARATION. 

2 
w 

tfc 

n-coifp. 

p-COMP. 

M-COMP 

p-COMP 

5856.312 

T 

Triple 

n.m. 

5859.809 
5862.582 

Sextuple? 
Triple 

2 
2 

0.698  Wi 
0.684 

W2 

2.033 

I    OOO 

5884.028 

Triple 

2 

0.436 

I    2  SO 

5905.895 
5914.335 

Quadruple? 

2 

W3 

0.658  Wi 

Wl 
W2 

I    880 

w-comps.  not  resolved 

5930.406 

Triple? 

2 

0.587  Wi 

Wi 

1.669 

5934.881 

Triple 

2 

0.589 

I    .672 

5952.943 

Triple? 

n.m. 

5975-575 

n.m. 

W2 

5977.007 

Triple 

2 

0.635 

I    777 

5983.908 

Triple? 

I 

0.608  Wj 

Wi 

1.698 

5985.040 

Triple 

2 

0.662 

1.848 

5987  .  290 

Triple? 

I 

0.624 

Wi 

I.74O 

6003  .  239 

Triple 

2 

0.772 

2  .  142 

6008.785 

Triple 

2 

0.652 

I    806 

6020.401 

Triple? 

2 

o  .  845  Wi 

Wi 

2  .332 

Diffuse 

6024.281 

Triple 

2 

0.649 

1.788 

6027.274 

T 

Triple 

2 

0.568 

I     l64. 

6042.315 

T 

n.m. 

W2 

w-comp.  blurred 

6056.227 

T 

Sextuple? 

I 

0.499  W2 

W2 

I  .361 

/i-comps.  diffuse,  p  almost   re- 

6065 .  709 

3 

Triple 

3 

0.403 

I    (XK 

solved 

6078.710 

T 

Triple? 

2 

0.635  wi 

Wi 

1.718 

Faint 

6102.392 

I 

Triple 

n.m. 

Faint 

6103.400 

T 

Sextuple? 

-,2 

n.m.   W2 

o.i;8« 

i   ^6^ 

6128.124 
6136.829 

I 

; 

Sextuple? 
Triple 

I 

3 

0.414  Wz 
0.515 

W2 

I.IO2 

I     367 

Faint  and  diffuse 

6137.915 

5 

Triple 

3 

o.  654 

I    7^6 

6141.938 

T 

Triple? 

2 

1  .017 

Wi 

2.696 

Faint 

6148.040 

T 

Sextuple? 

I 

0  .  649  W2 

Wl 

I    717 

Very  diffuse 

6149.458 
6157.945 

I 
T 

Quadruple 
Triple? 

1,1 

2 

0.812 

0.719 

0.740 

Wi 

2.148 
1.896 

1-950 

Enhanced  line 

6165.577 

T 

Sextuple? 

n.m.    W2 

W2 

6170.730 

T 

Sextuple? 

2 

0.725  W2 

W3 

1  .904 

p-comp.  almost  resolved 

6173.553 

T 

Triple 

2 

1  •  59° 

4.   171 

6180.420 

T 

Triple? 

n.m. 

Wl 

Faint 

6188.210 

I 

Triple 

n.m. 

Faint 

6191.779 

5 

Triple 

3 

o.  541 

I    4.1  1 

6200.527 

i 

Sextuple? 

I 

I  .026  W2 

Ws 

2  .  660 

Comps.  diffused 

6213.644 

i 

Sextuple 

2,3 

Pair    II,  1.603  (i) 
Pair     I,  0.798  (i) 

0.572 

4.ISI 

2    06? 

1.481 

6215.360 

T 

Triple 

2 

0.583 

I  -  ^OQ 

6219.494 
6230.943 

I 

6 

Sextuple? 
Triple 

2,2 

3 

0.991  wj 
0.767 

0.385 

2.562 
I  .976 

0-995 

6232.856 

i 

Sextuple? 

2 

i  .  205  wi 

W2 

^     IO2 

6238.598 
6246.535 
6247.774 

i 

2 

T 

Sextuple? 
Sextuple? 
Septuple? 

1,1 
2,2 

I 

i  .  042  wi 
0.958  wi 

0.670  W-2 

0.512 
0.278 

Ws 

2.677 
2.456 
I    7l6 

I-3I5 
0-713 

Enhanced  line 
Enhanced  line.    «-comps.  very 

6252.773 

3 

Triple 

3 

0.582 

1.488 

diffuse.    Probably  3  ^-comps. 

6254.456 

i 

Triple 

3 

o.  952 

2    4.24. 

6256.572 
6265.348 
6270.442 

i 
i 

T 

Sextuple? 
Sextuple? 
Triple? 

-,2 
2,2 

n.m.   ws 

0.969  W2 

n.m. 

0.696 
0.278 

Wi 

2.469 

1.778 
0.708 

n-comps.  very  diffuse 

6291  .184 
6298.007 

I 
T 

Sextuple? 
Sextuple? 

I 

1.014 
n'm.   W2 

W2 
W3 

2.562 

6301.718 
6302  .  709 
63IS-5I7 

6318.239 
6322.907 
6331.067 
6335  •  554 
6337.048 

3 
i 
i 

3 

i 
i 
3 
3 

Sextuple? 
Triple 
Sextuple? 

Triple 
Triple 
Sextuple? 
Septuple? 
Sextuple 

2,2 
2 

I 

2 

2 
I 
2 
2,2 

1.063  W2 

1.618 
o  .  906  Wi 

0-452 
0.965 

0.820  W2 
O.665  W2 

Pair   II,  1.641  (i) 
Pair     I,  0.946  (i) 

0.392 
W2 

Wl 
W3 
0.632 

2.676 

4-073 
2.271 

1.132 

2.414 

2.046 

1.656 
4.086 
2-356 

0.987 
1-574 

w-comps.  probably  double 

Faint,    p-comp.  almost  resolved. 
Enhanced  line 

Very  faint 
Probably  3  ^-comps. 

34          INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 
TABLE  i. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  IRON — Continued. 


7. 

CHARACTER 

Ej 

A 

X 

AX 

A2 

y. 

t—  1 

SEPARATION. 

O 
U 

W-COMP. 

£-COMP. 

W-COMP. 

/»-COMP. 

6330  006 

I 

Triple? 

n.m. 

Very  faint 

6^44.   371 

I 

Sextuple? 

I 

o.  771  wi 

n.m. 

i  016 

Very  faint.    />-comp.  double 

6  3  c  ?  .  24.6 

T 

Triple 

I 

0.730 

1.  808 

Very  faint 

6358.898 

f 

Sextuple? 

I 

O  .  746  W2 

Wi 

1.845 

Very  faint 

6380  958 

T 

Triple 

I 

0.464 

1  .  140 

Enhanced  line 

6303  820 

g 

Triple 

2 

o  SQ3 

I   4^0 

6400  217 

0 

Septuple? 

2 

o  802  Wi 

W2 

i  q<;8 

H-comps.  slightly  fringed.    Prob- 

6408   233 

x 

Septuple? 

—t2 

n.m. 

O    34^  (i) 

o  837 

ably  3  close  /J-comps. 
Apparently   4    weak     w-comps. 

o.ooo  (2) 

o  ooo 

about  equally  spaced 

O    ?4O  (i) 

o  852 

6411.865 

6417   133 

5 

x 

Septuple? 

? 

2 

I 

0.686  w2 

I    Ol8  W2 

W3 
W3 

1.668 

2    d72 

w-comps.   fringed,    probably    3 
/>-comps  . 
n~    and    />-comps.  very  diffuse. 

X 

Sextuple? 

I 

O    74.2.  W? 

Wj 

I  802 

Enhanced  line 
ff-comps  diffuse.   Enhanced  line 

6421     57O 

£ 

Triple 

7 

o  003 

2    408 

643  I  .  066 

t 

Sextuple? 

2 

o.  775  wi 

Wi 

1.87? 

64^6    63O 

X 

Triple? 

I 

o  840  Wi 

Wi 

2    O27 

Diffuse 

6456  .  603 

6462  06  «c 

x 

x 

Sextuple? 
Sextuple? 

2 
—  }2 

0.781  Wi 
n.m. 

W2 

o  ^8t; 

1.873 

I   400 

Enhanced  line.   Possibly  diffuse 
triplet 

H-comps.  faint  and  diffuse 

6469  408 

x 

? 

n.m. 

W-2 

Very  faint 

x 

? 

n.m. 

W2 

Very  faint 

64O  <C    213 

a 

Triple 

3 

o  682 

I    6l7 

6  si  8  SQO 

x 

Triple 

I 

0.837 

I  .970 

Very  faint 

6C46    470 

x 

Triple 

2 

o  ^84 

I    363 

6^60  460 

x 

Triple 

I 

O   Q2I 

2  .  1  34 

Close  to  air  line.  Enhanced  line 

Sextuple? 

p-comp.    apparently     double. 

6^03  161 

X 

Triple 

3 

0.699 

I.  608 

Very  faint 

x 

Sextuple? 

—  2 

n.m.   Wi 

O    <7O 

I    332 

Very  faint 

6627    7Q7 

x 

Triple? 

n.m. 

Wi 

Very  faint.    Enhanced  line 

Triple 

Very  faint 

Triple 

2 

i  088 

9     44  2 

Enhanced  line 

6678    23<; 

« 

Triple 

7 

o  787 

I  .  76  C 

MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  TITANIUM. 
TABLE  2. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  TITANIUM. 


35 


^ 

g 

Cfl 

CHARACTER 

| 

A 

X 

AX 

,V 

A 

SEPARATION. 

3 

tt-COMP. 

p-COKP. 

M-COMP. 

p-COMP. 

3659.901 

TO 

Triple 

2 

o.  243 

I    814 

3660.774 

? 

Quadruple? 

-,2 

n.m. 

0.188 

I  .403 

3662.378 

3669.106 

3671.819 
3679.821 
3685.339 

3690.053 
3706.363 

3710  094 

IO 
2 

3 
3 

20 
2 

8 

? 

Triple 
Triple 
Quadruple? 
Quadruple? 
Triple 
Triple 
Quadruple? 
Quadruple? 

2 

-,2 
2 

2,3 

0.199 
n.m. 
n.m. 
n.m. 

0.232 
n.m. 

O.  2OI   Wl 

0.161 

W2 
0.139 

1.484 

1.708 
1.463 

I.I94 
I  .OI2 

Enhanced  line 
Enhanced  line 

3717.  539 

7, 

Quadruple? 

n.m.    wz 

W2 

2721  .  770 

5 

Quadruple? 

3 

2    48^ 

3722.729 

T, 

Triple? 

i 

O-  J45 

Wi 

I  .046 

3724.  716 

^ 

Triple 

2 

O    24? 

I    7^1 

3725.300 

•3, 

Triple? 

I 

o.  261 

Wi 

I.88I 

3729.952 

<] 

Triple 

3 

o  142 

I    O2I 

3741  .  205 

7 

Triple 

3 

o  248 

I    772 

3741.791 

TO 

Triple 

3 

o.  263 

1.878 

3748.  232 

6 

Triple 

2 

o  100 

I    3=12 

3753.003 

5 

Triple 

3 

0.277 

1.967 

3753  .  732 

3 

Quadruple? 

2 

O    374 

W2 

2    6<A 

3757  824 

6 

Triple 

2 

3759.447 

70 

Triple 

2 

o  288 

2    O^8 

3761  .464 

TO 

Triple 

2 

O    2O7 

3762.012 

^ 

Triple 

3 

o.  253 

1.788 

3771  .  798 

^ 

Triple? 

2 

o  3<;6 

Wi 

2     <O2 

3776.198 
3786.181 

4 

3 

Triple? 
Triple 

2 

3 

0.336 
o.  229 

Wl 

2-357 
i   S98 

Enhanced  line 

3813  .  537 

3 

Quadruple? 

2 

0    288  Wi 

Wi 

i  980 

3814.671 

-\ 

Sextuple? 

2 

0.319  W2 

W2 

2  .  IQ2 

3836  .  229 

3 

Triple? 

2 

O    34.1 

Wi 

2     71? 

3853.872 

7, 

Triple? 

2 

o.  267 

Wl 

1.798 

3858.262 

7, 

Triple? 

2 

0.278 

Wi 

1.868 

3866.577 

7 

Triple 

2 

o  284. 

I    OOO 

3868.539 

7, 

Triple? 

2 

0.343 

Wi 

2  .  2O2 

3875  .425 

7, 

Triple 

2 

O    ^22 

2    144 

3882.309 

7, 

Triple 

2 

0.325 

2.157 

3882.439 

/\ 

Sextuple? 

2 

O    3  GO  Wi 

W2 

2.648 

3883.033 

3 

Triple 

2 

I    8^O 

3895.377 

t 

Triple? 

2 

O.  3OQ 

Wj 

2.O37 

3900.681 

5° 

Triple 

3 

O    272 

I     787 

3QO4.    026 

5 

Triple 

3 

3913.609 

7.n 

Triple 

3 

o  219 

I  .4^0 

3QI4-477 
3Q2I  .563 

2 

7, 

Sextuple? 
ii  comps.? 

2,3 

i,— 

0.352  w2 
0.340  (l) 

0.206 

n.m. 

2.298 
2  .  2IO 

1-345 

Probably    two    pairs   />-comps. 

o  224  (3) 

I    4"*6 

O   6  SO 

o  ooo  (3) 

O    OOO 

o  631 

0.198  (3) 

1.287 

O    32O  (l) 

2    080 

3924-673 
3926.465 

3 

7, 

Octuple? 
Triple 

2,3 

3 

O.292  W2 

o  247 

0.162 

1.895 

1  .602 

1.052 

Probably  3  pairs  w-comps. 

3930.022 

3 

ii  comps? 

2,3 

0.264  (l) 
O.lS?   (3) 

0.292 

1.709 

I.  211 

1.890 

Trace   of   inner   pair  ^-comps. 
Compare  X  3921  .563 

O    OCK   (2) 

O   6l< 

3932.l6l 

3947.918 
3948.818 
3956.476 

3958.35S 
3962.995 

4 
3 

4 
5 
3 

? 

? 
Triple 
Sextuple? 
Triple 

? 

2 
2 

3 

2 

3 

2 

o.ooo  (3) 

0.094  (2) 
0.178(3) 
0.267  (l) 

0.406  W2 

0.098  w2 
0.186 
0.229  wi 
0.287 

0.461   W2 

W2 
W2 
Wi 
W2 

0.000 
0.609 
I.IS2 
1.729 
2.626 

0.629 
I-IQ3 
1-463 
1.832 

2-935 

Enhanced  line,     w-comps.  have 
strong  inner  fringes 
«-comps.  strongly  fringed 

w-comps.  fringed 

«-comps.     have     strong     inner 
fringes,  similar  to  X  3932  .  161 

36  INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

TABLE  2. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  TITANIUM — Continued. 


7 

CHARACTER 

Ej 

A 

X 

AX 

/X" 

Z 

HH 

SEPARATION. 

o 
£ 

W-COMP. 

p-COMP. 

n-cowp. 

£-COMP. 

1064.  4.16 

2 

Sextuple? 

2 

O    2CQ  Wi 

Wi 

2    28? 

Probably  inner  pair  «-comps. 

3081  .017 

3 

Triple 

2 

o  188 

I.I86 

3982  .  142 

2 

Sextuple 

2,2 

Pair   11,0.390  (i) 
Pair     I,  o  151  (i) 

0.311 

2.460 

O    (K2 

1.961 

3982.630 

3 

10  comps.? 

2,1 

Pair  III,  0.784  (i) 
Pair   II  o  475  (2) 

0-565 

4.942 

2    OQ4. 

3-56I 

Probably  weak   inner    pair    p- 
comps.     Difficult   blend  with 

Pair     I,  o  148  (4) 

O     Q77 

two  preceding  lines 

2087  .  71$ 

i 

Triple 

n  m 

Enhanced  line 

3989.912 

ft 

Triple 

O    27$ 

I  .  727 

3998.790 

6 

Triple 

7 

O.  7T7 

I  .720 

Unsymmetrical.    M-comps.  have 

4.OOO   O7Q 

4 

Sextuple? 

Ws 

2    I  CO 

inner  fringes,  broader  for  violet 
comp.  ^>-comp.  fringed  toward 
violet 

4009.807 

2 

2 

o  086 

? 

O    <*< 

Unsymmetrical.   Violet  »-comp. 

4012.541 
4021.893 

4 

2 

Octuple? 

? 

2,3 

0.198  w2 
n.m. 

0.169 

1.230 

1.050 

3  times  strength  of  red.     p- 
comp.  hazy,  displaced  toward 
violet 
Enhanced  line.  Probably  3  pairs 
w-comps. 
n-comps.  diffuse,  narrowly  sep- 

4024. 726 

7 

Sextuple? 

arated,     p-comp.  fairly  sharp 
K-comps.  have  inner  fringes 

4025  .  286 
4026.69! 

| 

2 

Sextuple? 
Triple 

2,3 

2 

0  .  263  W2 

o  220 

o.  129 

1.623 

I      3C? 

0.796 

Enhanced  line 

4028  .  497 

C 

Triple 

I  658 

Enhanced  line 

4030  .  646 

2 

Triple? 

O    24.7,  Wi 

Wi 

i  40=; 

4035.976 

2 

Triple 

2 

O    3.S4 

2  .  173 

4053.981 

5 

Triple 

I    412 

Enhanced  line 

4055.189 

3 

Triple 

^ 

O    ?CK 

2    4O2 

Enhanced  line 

4060.415 

3 

Triple 

2 

O    ^Ol 

2  .  ?o6 

4064.362 

2 

Triple 

2    ^08 

4065  .  239 

3 

Triple 

O    3QC. 

2    7,QO 

4078.631 

4 

Triple 

7 

O.  Tnc 

2.374 

4082  .  589 

3 

Triple 

o  308 

2    X88 

4112.869 
4122.306 

2 
2 

Sextuple? 
Triple 

1,2 

0.3OI   W2 

o  261 

0.236 

1.779 

i   1^6 

1-395 

n-comps.  very  diffuse 

4123.713 

2 

Triple 

2 

o  264. 

I  .  C.<.2 

4127.689 

3 

Triple 

2 

O.  2QI 

1.708 

4137.428 

2 

Triple 

o  ^6<; 

2    133 

4151.129 

3 

Triple 

7 

o  3OC 

I  .770 

4159.805 

2 

Triple 

I    52O 

4161.682 

Sextuple? 

2    858 

Enhanced  line,     n-comps.  have 

4163.818 

2O 

Triple 

I    696 

inner  fringes 
Enhanced  line 

4171.213 

2 

Triple 

2 

O    2IO 



I    2O7 

4172.066 

15 

Triple 

7 

O    2^1 

T     ^^-> 

Enhanced  line 

4173.710 
4184.472 

3 

i 

Sextuple? 

2,2 

0.361  Wi 
n.m.  wz 

0.096 

W3 

2.072 

0.551 

Enhanced  line 
Enhanced  line,  all  comps.  diffuse 

4186.280 

2 

Triple 

o  282 

I  600 

4200.946 

Triple? 

'  Wi'  ' 

Faint  in  spark 

4203.620 

2 

Triple 

2  ic86 

Faint  in  spark 

4238.050 

2 

Triple 

o  286 

i   ^02 

4256.760 
4261  .  748 
4263  .  290 
4270.329 
4272.701 

4274.746 
4276.587 
4278.39° 

2 

2 

4 

2 

4 

Sextuple? 
Triple? 
Triple 
Sextuple? 
Septuple? 

Triple 
Sextuple? 
Triple 

2 
2 

3 
2,2 
2 

3 
2 

3 

0.396  Wi 
0.324  Wi 

0.331 

0.378  W2 

0.364  w2 
0.291 

0.443  Wl 

0.304 

Wi 

0.248 

Wi 

W2 

2.186 
1.784 
1.821 
2.073 
1.994 

1-572 
2.422 

1.661 

1.360 

X  given  by  Fiebig  as  4272-581 
agrees  better  with   solar   line 
X4272.5OO.  n-comps.have  inner 
fringes.   Probably  3  p-compa. 

n-comps.  have  inner  fringes 

MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  TITANIUM. 
TABLE  2. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  TITANIUM — Continued. 


37 


x 

>< 

H 

CHARACTER 

OF 

i 

iX 

A 

Vx2 

z 

HH 

SEPARATION. 

o 
H 

»-COMP. 

p-coitp. 

n-CGMP 

p-COMP 

4281.530 

1 

Octuple 

3,3 

o  .  444  (4) 

2    422 

0.218  (2) 
o.ooo  (i) 
0.218  (2) 
0.448  (4) 

0.222  (2) 

o.ooo  (3) 

O.224  (2) 

I.I89 

O.OOO 

1.189 

2    44.3 

I.  211 

O.OOO 
1.222 

4282.860 

3 

Triple 

3 

o.  244 

• 

4285.164 
4286.168 
4287.566 
4288.038 

4289.237 

5 
4 
4 
2 

4 

Quadruple? 
Sextuple? 
Sextuple? 
Septuple? 

12  Comps. 

3 

2,3 
2,3 

2 

2,3 

0.566 
0.400  W: 
0.421  wi 
0.516  w^ 

Pair  IV,  0.586  (i) 
Pair  III,  0.443  (2) 
Pair   11,0.306  (2) 

W! 

0.166 
0.146 

W3 

Pair   II,  0.288  (6) 
Pair     I,  0.140  (i) 

3-083 
2.177 
2.290 
2.806 

3-186 
2.408 

i  66? 

0.904 

,   °  794 

1-566 
0.761 

»-comps.    have    inner    fringes. 
Probably  3  p-comps. 

Pair     I,  0.144  (i) 

o  78* 

4290.377 

10 

? 

2 

0  .  284  Wi 

Wi 

I  .  CA-1 

«-comps.  strongly  fringed     3  or 

4291.114 

2 

Quintuple 

3,3 

0.221   (i) 

o.ooo  (2) 

0-445 

I.  ZOO 

O.OOO 

2.417 

more  />-comps.    Enhanced  line 

O.22O  (i) 

I    I(K 

4291.375 

2 

Triple 

i 

o.  210 

4294.204 

10 

Triple 

3 

0.361 

i  0*8 

Enhanced  line 

4295-914 
4298.828 

4 

4 

Unaffected 
Septuple 

2,3 

Pair   II,  0.292  (i) 
Pair     1,0.145(5) 

0.060  (2) 
o.ooo  (3) 
0.086  (2) 

1.580 
0.784 

0.325 
o.ooo 
o  465 

p-comps.  distinctly  unsymmet- 
rical 

4299.410 

1 

Quadruple? 

i 

0.430 

Wl 

2.327 

4299.803 

2 

Triple? 

i 

0.356 

Wi 

1  .021; 

4300.211 

& 

p 

2 

0.367  wi 

Wi 

1.985 

K-comps.  fringed.     3  or  more  p- 

4300.732 

2 

Septuple? 

2 

o  .  265  wi 

W] 

1  .4.22 

comps.    Enhanced  line 
M-comps  fringed  probably  3  p- 

4301  .  158 

•? 

Triple? 

0.350 

Wi 

1.892 

comps. 

4302.085 

5 

Sextuple 

3,3 

Pair   11,0.585  (i) 
Pair     I,  0.151  (3) 

0.016 

3.161 
o  816 

1.167 

Enhanced  line 

4306.078 

8 

Septuple? 

2 

0.367  Wi 

W2 

I    O70 

K-comps.  fringed  probably  3  p- 

4308.081 

8 

Octuple 

2,2 

Pair  III,  0.588(1) 
Pair   II,  o  442  (2) 

0.236 

3.168 

2    382 

1.272 

comps. 
Blend  with  iron  impurity  line 

Pair     I,  0.291  (3) 

i  <;68 

4311.880 

i 

Sextuple? 

2 

0.147 

Wi 

0.791 

comps.    Enhanced  line 
Outer  pair  n-comps.  not  measur- 

4313.034 
4314.964 

8 
1 

Sextuple? 
Triple 

2,2 

3 

0.449  W2 
0.424 

0.159 

2.414 

2  •  277 

0.855 

able.      Possibly    3    ^-comps. 
Blend  with  faint  lines 
Enhanced  line 

4315-138 
4316.962 

5 

3 

Quadruple 
Triple 

3,3 
3 

0.392 
0.207 

0-349 

2.105 
I     III 

1.874 

Enhanced  line 

4318.817 

^ 

Triple 

3 

0.337 

1.807 

4321.119 

3 

Sextuple 

3,3 

Pair   11,0.785  (2) 
Pair     I,  0.257  (0 

0.261 

4.204 
I    .376 

1.398 

Enhanced  line 

4321-813 

1 

Triple 

2 

o.  310 

I        660 

4323-531 

I 

Triple 

2 

0.464 

2    4.82 

4325.306 

^ 

Triple 

a 

0.301 

4326.520 

2 

Triple 

• 
3 

0.403 

2    1*2 

4330-405 

1 

Sextuple? 

2 

0.415  Wi 

Wi 

2.  213 

Enhanced  line 

4330.866 

4338.084 
4341.530 

3 

10 
1 

? 
Triple 

2 

3 

O  .  654  Wl 

0.247 
Wj 

w, 

Wi 

3-487 
1.312 

Enhanced  line,     w-comps.  have 
inner  fringes 
Enhanced  line 
Enhanced  line       Probably  nu- 

4344.451 
4346.278 
4351.000 
4354.228 
4360.644 

3 

2 
2 
2 

2 

Sextuple? 
Sextuple? 
Triple 
Quadruple? 
Triple 

2 

2 

3 

2 

3 

0.474  wi 

0-453  Wl 

0.387 

0.300  wi 

0.348 

Wl 

w. 
w. 

2.512 
2.308 
2-044 
1-583 
1.830 

merous    close    «-comps,    not 
resolved,  center  strong 
Enhanced  line 

Enhanced  line 

3  8          INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 
TABLE  2. — MEASUREMENTS  or  ZEEMAN  EFFECT  FOR  TITANIUM — Continued. 


>  1 

w 

CHARACTER 

- 

A, 

b 

AX/ 

X2 

1 

HH 

SEPARATION. 

§ 

W-COMP. 

p-COVP. 

M-COMP. 

p-COMP. 

4767    8^O 

6 

Triple 

7 

O    7,7,2 

I    74O 

Enhanced  line 

Triple 

Triple 

O    7.14 

i  64^ 

2 

Triple 

2 

o  774 

I    745 

Enhanced  line 

Triple 

I    528 

4391.192 

2 
2 

Septuple? 
Triple 

2 

2 

0.304  W2 
O    72<J 

Wj 

1-577 
i  68-« 

Enhanced  line.     Probably  4  «-, 
3  />-comps. 

4204    22< 

2 

Triple 

2 

O.42O 

2.175; 

2O 

Triple 

O    347 

i  706 

4396  .  008 
4398.460 

47QQ     Q7C 

2 

I 

6 

Triple? 
Quadruple? 

Triple 

3 

2,3 

7 

0-374 

0.144 

O.47I 

Wi 

0.224 

1-935 
0.744 

2    226 

I.I58 

Enhanced  line 
Possibly  faint  outer  n-comps,  but 
not  visible  on  strong  photograph 
Enhanced  line 

Triple 

2 

O   411 

2    IIO 

AAQC     O82 

i 

Triple 

I 

O    71  6 

I    628 

440=;  .806 

i 

Sextuple? 

—  7 

n.m.  Wa 

0.314 

I  .617 

4409.408 

4.400  68^ 

i 

T 

Sextuple? 
Sextuple? 

M 

—,i 

0.523  wi 
n  m    Wa 

0.171 
o.  248 

2.690 

0.880 
I    27^ 

c 

Triple 

44.17    4^0 

2 

Triple 

o  381 

4417.884 

A4l8    4.OQ 

6 

2 

10  comps.? 
Sextuple? 

2,2 
2 

Pair   II,o.288(i) 
Pair     I,  o.i  20  (2) 
o  402  Wi 

Pair   II,  0.240  (2) 
Pair     I,  0.072  (3) 

Wi 

1.476 
0.615 

2    OOO 

1.230 
0.369 

Probably  weak   pair   n-comps. 
outside.     Enhanced  line 

2 

Triple 

I    478 

4422.104 
4422    08^ 

2 
2 

Quadruple? 
Triple 

2,1 

2 

0.358  wi 

O    777 

0.107 

I.83I 
I    .Q27 

0-547 

I 

Triple 

2 

4.426    2OI 

2 

Triple 

2 

0    7,l8 

I        623 

4427    266 

4 

Triple 

7 

O    712 

I     ^02 

2 

Sextuple? 

2 

W] 

2    78A 

44.21    4C7 

I 

Triple 

2 

O    I  C4 

o  784 

4427  .  74.2 

I 

Triple 

7 

o  187 

O    QCI 

a 

Triple 

I    717 

44.26    7CO 

2 

Sextuple? 

2 

o  466  Wi 

Wf 

2    7.6? 

4438.359 
4440.515 
4  4  -JT  433 

I 
2 

j 

Sextuple? 
Sextuple? 
Quadruple? 

1,2 

2,3 

I 

0.441  Wa 
0.270  Wi 

O    417  Wi 

0.180 

0.168 

W2 

2-239 
1.369 
2    OO4 

0.914 
0.852 

I  c 

Triple 

Enhanced  line 

4444.728 

I 

Sextuple? 
Triple 

2,2 

0.317  w, 
o  388 

0-24S 

1.604 

1.240 

4450.654 

4 

10  comps.? 
Triple 

2,3 

0.388  w» 

0.264  wi 

1-958 

I    7l6 

1-333 

Probably  6  «-,  4  p-comps.     En- 
hanced line 

44  c  7    486 

a 

Triple 

7 

O    2IO 

I    OSQ 

Quadruple  ? 

Wi 

AACC    48? 

Triple 

7 

I    768 

Triple 

Wa 

2    ^^4 

446  7    84? 

I 

Triple  ? 

I 

o  509 

Wi 

2    ^?4 

4464.617 

2 

Quintuple 

2,3 

0.285  (O 

0.287 

1-430 

O   OOO 

1.440 

Enhanced  line 

446  c  Q7C 

7 

Wi 

2    4.12 

4468  663 

Triple 

Enhanced  line 

Triple 

4471.017 
4471.408 

4475-026 

4479-879 
4480.752 
4481.438 
4482.904 

2 

2 

2 

2 

I 
3 

2 

10  comps.? 
9  comps. 

Septuple? 
Triple 
Triple 
Triple 
Sextuple? 

2,2 
2,2 
2 

3 

2 

3 

2 

Pair  III,  0.724  (i) 
Pair   11,0.386  (i) 
Pair    I,  0.126  (i) 
Pair  III,  0.826  (i) 
Pair   II,  0.613  (2) 
Pair     1,0.364(4) 
0.509  wi 
0.829 
0.611 
0.548 
0.498  Wi 

0.458 
0.113  (2) 

o.ooo  (3) 
0.116  (2) 
w, 

Wa 

3.622 

I-93I 
0.630 

4.132 
3.066 
I.82I 
2-542 
4.130 

3-043 
2.729 
2.478 

2.292 
0.565 

0.000 

0.580 

Trace  of  inner  pair  p-comps. 
Probably  4  n-,  3  p-comps. 

MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  TITANIUM. 
TABLE  2. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  TITANIUM — Continued. 


39 


x 

>< 

H 
% 

CHARACTER 

| 

i 

iX 

A> 

/x2 

1 

hH 

SEPARATION. 

a 

n-cottp. 

p-COIfP. 

n-coMp. 

p-COUP. 

4488  .  493 

6 

Triple 

3 

0.355 

i  762 

4489  .  262 
4495.182 

3 

i 

9  comps. 
Triple 

2,2 

I 

Pair  III,  0.858  (i) 
Pair   II,  0.597  (2) 
Pair     1,0.382(4) 
0.353 

O.III    (2) 

o.ooo  (3) 
o.no  (2) 

4.258 
2.963 
1.896 

I    74-7 

0.551 

o.ooo 
0.546 

Compare  X  4471  .408 

4496.318 

3 

Triple 

3 

O.4Q3 

4497.842 

T 

Triple 

2 

O    C24 

4501.445 

TI; 

Triple 

3 

o.  298 

I    471 

Enhanced  line 

4512.906 

4 

Triple 

3 

O.  SOI 

4518.198 

4 

Quadruple? 

3 

0.498 

Wi 

•2    44O 

4518.866 

I 

Triple 

2 

O.  22O 

I    O77 

4522.974 

4 

Sextuple? 

3 

0.502  W| 

W2 

2    4C4 

4527.490 

4 

Octuple 

3,3 

0.324  (?) 
0.162  (2) 
0.000  (i) 

0.166  (4) 

0.164  (i) 

o.ooo  (2) 

0.165  (i) 

I.58l 
0.790 
0.000 

0.800 
o.ooo 

0.805 

0.338  (7) 

I    64O 

4529.656 
4533-  4J9 

2 

<; 

Sextuple? 
Triple 

2,2 

3 

0.358  w2 
0.469 

0.278  Wi 

1-745 

2    282 

1-355 

Enhanced  line 

4534.139 

6 

Triple? 

0.360  Wi 

Wi 

4534.953 

4 

Triple 

3 

0.449 

2    l8? 

hanced  line 

4535.741 

^ 

Triple 

3 

o  424 

4536.094 

s 

Triple 

2 

0.323 

I    ^7O 

4536.222 

3 

Unaffected? 

No  resolution.  Blend  with  36  094 

4537.389 

I 

Triple 

I 

0.355 

1  .  72C 

may  conceal  slight  widening  of 
»-comp. 

4544-iQO 
4544  .  864 

I 
3 

Quadruple? 
Octuple 

I 

3,3 

0.308 
0-334  (7) 
0.168  (2) 

0.000  (i) 

0.170(4) 

O    312  (?) 

W2 

0.171  (i) 

o.ooo  (2) 

0.166  (i) 

1.492 
1.617 
0.813 

o.ooo 

0.823 

0.828 
o.ooo 
0.804 

Comps.  in  all  respects  similar  to 
X  4427.  490 

4548.938 
4549  .  808 

3 

70 

Septuple? 
Triple 

2 

3 

o  .  560  Wi 
o  440 

W2 

2.706 

2    I2S 

n-comps.    have    inner    fringes. 
Probably  3  p-comps. 

4552.632 

4 

Quadruple? 

3 

0.510 

Wi 

2    460 

4555-662 

^ 

Triple 

3 

o.  <;o6 

2    4^8 

4560.102 

T 

Triple 

2 

O  44.6 

4562.814 

T 

Triple 

3 

0.424 

'f-145 
2    036 

4563  .  939 

TO 

Triple 

3 

o  276 

4568.499 
4571.095 

I 
T 

Quintuple? 
Triple 

~,2 
2 

n.m. 

O.22I 

0.293 

i  o<c8 

1.404 

Only   central    7i-comp.   visible. 
Line      probably     similar     to 
X  4464.  617 

4572.156 

70 

Triple 

3 

o  319 

4590.  126 

3 

Octuple 

2,3 

Pair  111,0.549  (2) 
Pair    II,  0.360  (3) 

0.288 

2.606 

1-367 

6  »-comps.  not  completely  re- 
solved 

Pair     I,  o  165  (2) 

o  781 

4599.408 

i 

Triple 

3 

0.423 

2    OOO 

4617.452 

4 

Septuple? 

2 

o  404  Wi 

W2 

i  8o< 

4623.279 

3 

Septuple? 

2 

0.379  W2 

W3 

I    772 

#-comps 
w-comps.  fringed.     Probably  3 

4629.521 

4638.050 

4639.538 
4639.846 

4640.119 
4645  .  368 
4650.193 

i 

2 
2 

2 
2 
2 

9  comps. 

Triple 
Octuple? 
Quadruple? 

Sextuple 
Triple 
Sextuple? 

3,3 
3 

2,2 
2 

3,3 
3 
3 

Pair  III,  0.873(1) 
Pair    11,0.535  (2) 
Pair     1,0.173  (4) 
0.528 
0.594  W3 
0-549 

Pair   11,0.864  (i) 
Pair     1,0.535(1) 
0.880 

o.733  w. 

0.172  (2) 

o.ooo  (3) 

0.180  (2) 

0.224 
n.m. 

0-353 

W2 

4.072 
2.496 
0.807 
2-455 
2-759 
2-550 

4-013 
2.485 
4.079 

3-390 

0.802 

0.000 

0.840 
1  .040 

1.640 

#-comps. 

Probably  3  pairs  n-comps. 
Blend  prevents  measurement  of 
p-comps, 

Violet  comp.  3/2  stronger  than 
red 

40  INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

TABLE  2. — MEASUREMENTS  OP  ZEEMAN  EFFECT  FOR  TITANIUM — Continued. 


> 
H 
CO 

CHARACTER 

| 

A 

X 

AX 

A' 

t-H 

SEPARATION. 

o 

H 

tt-COMP. 

p-COtfP. 

fl-COMP. 

p-COUP. 

4,6  cfi  644 

7 

Triple 

7 

O    2QS 

1  .  360 

? 

Wj 

Wj 

Not  resolved.  «-comp.  has  strong 

4667   768 

Triple 

2 

I   602 

center  with  fringes.  Enhanced 
line 

Triple 

2 

o  c;o6 

2    31? 

4682  088 

Triple 

I   820 

^688    CS4 

Triple 

2 

I    ?74 

4.6OI     <s2^ 

Triple? 

•2 

r>   AAJ 

Wl 

2    OO3 

Triple 

2 

0    S.SS 

Sextuple? 

2 

O   367  W2 

Ws 

I  662 

n-comps.  fringed 

47IO    ^68 

Quintuple 

Pair   II,  0.486  (i) 

2  .  191 

Single  sharp  p-comp.    Only  line 

Pair     I  o  183  (i) 

o  82? 

of  type  in  spectrum 

4722.797 

2 

Sextuple 

2,3 

Pair    11,0.555  (i) 
Pair     I,  o.  224  (i) 

0.390 

2.488 
I  .004 

1.748 

4723-359 

A77  I      2C6 

2 
2 

Sextuple? 
Triple? 

2,2 
2 

0.453  w2 
o  412 

0.226 

Wl 

2.031 
841 

1.013 

H-comps.  fringed 

Triple 

2 

?62 

4.74.2    Q7O 

e 

Triple 

1 

O    2Os 

7U 

471:8  ^08 

a 

Triple 

2 

o  382 

.687 

8 

Triple 

7 

Soc) 

4.764  108 

i 

Triple? 

Enhanced  line.    Unresolved  H- 

4.760  ooi 

2 

O    583  W2 

W2 

2    <62 

comp.    Diffuse 

4778.441 

4780.169 

4.781    QI7. 

3 
5 

2 

Sextuple? 
Quadruple 

2,2 

3,2 

—.1 

0.338  W2 
0.498 

n  m     Wa 

0.184 

0.243 

O     ^14  W2 

1.481 
2.180 

0.806 
1.064 

I      277 

Enhanced  line 
All     comps.    wide    and     hazy. 

4792    7O2 

7 

Sextuple? 

2 

O    37O  Wa 

W2 

i  .6n 

Probably  3  pairs  «-,  2  pairs  p- 
comps. 

Triple? 

2 

o  848 

4798.169 

I 

Sextuple 

1,2 

Pair   11,0.594  (2) 
Pair     I,  o  218  (i) 

0.388 

2.580 

O.Q47 

1.685 

4798-293 
4799.984 
4805.285 

I 

3 

10 

? 
Sextuple? 
Sextuple 

2,2 
2,2 

W3 

0.329  w2 
Pair   11,0.643  (i) 
Pair     I  o  ^64  (^) 

Wj 

0.182 
0.149 

1.428 
2.785 

I    <77 

0.790 
0.645 

>i-comps.  diffuse,  not  resolved 
Enhanced  line 

4805  606 

Triple? 

i   7^:8 

4808  7« 

Triple? 

Wi 

i  6<;6 

4.811  .  27C 

i 

Triple 

2 

I    72O 

Triple 

I    678 

4827  804 

Triple? 

Wi 

I    77.7 

Triple 

I    ^^6 

484.1    O74 

6 

Triple 

I    664 

4848  .  60S 

2 

Triple 

o  516 

2    IQ? 

4,8c6  203. 

Triple 

1     70  i 

4864  362 

Triple 

i  864 

4.86?  708 

Sextuple? 

Titanium? 

4868  4<;i 

Triple 

i   ^^8 

487O    3.27. 

e 

Triple 

i  640 

Triple 

Enhanced  line 

488I.I28 

Triple 

o  831 

4881;    264 

8 

Triple 

I      78l 

4QOO   OQS 

6 

Triple 

I     64  "\ 

ft 

Triple? 

Enhanced  line 

401^   803 

8 

Triple 

T     AAJ 

49I5-4I4 
4920.047 
4921  .963 

i 
3 

Sextuple? 
Triple 
Triple 

2,2 
3 

O.4I5  W2 

0.387 

0.234 

1.718 

1-599 
i  812 

0.969 

4925.594 
4926.334 
4928.511 

4938.467 
4968  .  769 

4975-530 
4978.372 
4981.912 
4989.325 

i 

i 

3 

3 
I 
I 
I 
10 

2 

Sextuple? 
Triple 
Sextuple? 
Triple 
Sextuple? 
Triple 
Quadruple? 
Triple 
Triple 

->I 

I 

2 

3 

-I  I 

3 

2 

3 
3 

n.m.    wj 
0.509 

0.268  W2 

0.392 

n.m.    wj 
0.414 
0.238  Wi 
0.481 
0.329 

0.365 

Wl 

0.358 

Wl 

2.098 
1.103 
i.  608 

1-673 
0.960 
1.938 
1.322 

I-5°4 
1-450 

MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  TITANIUM. 


TABLE   2.  —  MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  TITANIUM  —  Continued. 


\ 

1 

CHARACTER 

j 

t 

,x 

AX 

A2 

1 

SEPARATION. 

i 

n-coMF. 

p-COMP. 

«-COMP. 

p-COUP. 

4991  .247 

TO 

Triple 

3 

o  458 

i  830 

4997  .  283 

2 

-,3 

n.m. 

o  415 

1.662 

Numerous     w-comps.     blurred 

4999  .  689 

IO 

Triple 

3 

0.413 

i  .652 

Red  n-  and  ^-comps.  stronger 
than  violet 

5001.165 

3 

Triple? 

3 

O.4OS 

Wi 

i  .610 

5007  .  398 

IO 

Triple 

3 

0.339 

1  .352 

5008.632 

I 

Triple 

2 

0.414 

1  .6  so 

5009.829 

T 

-,2 

n.m. 

o  279 

I    112 

5010.396 

I 

Triple? 

2 

0.354 

W] 

i  .410 

5013.479 

s 

Triple 

3 

0.455 

1.811 

5014.236 

4 

Triple 

I 

0.177 

0.704 

Titanium? 

5014.369 

5 

Triple 

2 

O.  217 

0.863 

5016.340 
5020.208 
5023  052 

5025.027 

7 
8 
8 

7 

Sextuple? 
Octuple? 
12  comps.? 

10  comps. 

2,3 
2,3 
2,3 

2,2 

0-543 
0.507  w3 
0.466  w3 

Pair  III,  0.684  (i) 
Pair   11,0.416  (2) 
Pair     I,  0.133  (4) 

0.214 
0.276 
0.370  w, 

Pair   11,0.546  (6) 
Pair     I,  0.269  (i) 

2.158 

2.OI2 
1.847 

2.709 
1.647 

O-  527 

0.851 

1-095 
1.466 

2.162 
1.065 

Probably  3  pairs  w-comps. 
Probably  4  pairs  w-comps. 
^-comps.  have  inner  fringes 

5025  .  749 

5 

Triple 

3 

0.471 

.86°; 

5036  .  089 

TO 

Triple 

3 

O   4.5S 

7O4. 

5036  .  645 

8 

Triple 

3 

0.436 

.718 

5038.579 

8 

Triple 

3 

O.  34O 

72Q 

5040.138 

8 

Triple 

3 

0.404 

.  ^QO 

5053  .  056 

g 

Triple? 

2 

0.449 

Wi 

I      7  CO 

5062  .  285 

3 

Triple? 

2 

0.412 

Wi 

i.  608 

5064  .  244 

T 

Triple 

n.m. 

Very  faint 

5064.836 

8 

Triple 

3 

0.463 

i  .805 

5066.174 

T 

Sextuple? 

-,i 

n.m.  Wa 

0.407 

i   <86 

5069  .  592 

2 

Triple 

2 

0.235 

0.914 

5071.666 
5072.479 

4 

6 

Sextuple? 
Triple 

1,1 

3 

0  .  47O  W2 

0.502 

0.275 

1.827 

I    OSI 

1.069 

Enhanced  line 

5087  .  239 

4 

Triple 

3 

0.329 

i  .271 

5113.617 

5 

Triple 

3 

0.431 

1.648 

5120.592 

7 

Triple 

3 

O.4.34 

i  6<c< 

5129.336 

8 

Triple 

3 

0.478 

i.  812 

Enhanced  line 

5145.636 

6 

Triple 

3 

O.4Q3 

i  862 

5147.652 

5 

Septuple? 

2 

O.8O5  W2 

Ws 

3.038 

Probably  more  than  7  comps. 

5152.361 

| 

Quadruple? 

3 

o.  671  Wi 

Wi 

2.1:28 

^-comps.  almost  resolved 

5154.244 

4 

Sextuple? 

2 

0.666  Wz 

Wj 

2.5O7 

Enhanced  line 

5173.917 

TO 

Triple 

7 

o.  292 

.OOI 

5186.073 

8 

Triple 

3 

0.385 

472 

Enhanced  line 

5188.863 

T? 

Triple 

0 

2 

O     ?I2 

5193.139 

TO 

Triple 

3 

0.468 

.  73C 

5201.260 

3 

Triple? 

2 

0.648  Wi 

Wi 

£ 

•39^ 

5206.215 

4 

Triple 

2 

5210.555 

TO 

Triple 

3 

0.547 

2  014 

5219.875 

4 

Sextuple? 

2 

0.326  (2) 

w-> 

i  .  191 

Unsymmetrical.     Probably  4  n- 

normal 

comps.,  2  violet  blended,  2  red 

o  264  (i) 

o  060 

0.400  (i) 

1.468 

0.062  to  violet  from  normal. 

5222.849 

S223-79I 

5224.471 
5224.712 
5225.198 
5226.707 
5238.742 
5247.466 
5252.276 

5255-973 
5260.142 
5262.321 

3 
3 

8 

5 
6 

IO 

3 

2 

3 
3 
i 

I 

Unaffected 
Triple 
Triple 
Triple 
Triple 
Triple 
Triple? 
Sextuple? 
Sextuple? 
Triple? 
Triple 
Sextuple? 

2 
3 

2 
2 

3 
2 

I 
2 
2 
2 
2 

0-437 
0.631 
0.608 
0.548 

0-349 
0.379  wi 

0.773  W2 

0.686  w2 
0.647  wi 
0.430 

0.739  W2 

Wi 
W2 
W2 
Wi 

W3 

1.887 
2.312 
2.227 
2.007 
1.277 
1.381 
2.808 
2.487 
2.342 

1-554 
2.671 



All  comps.  measured  from  nor- 
mal 

Enhanced  line 
Enhanced  line 

42          INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 
TABLE  2. — MEASUREMENTS  or  ZEEMAN  EFFECT  FOR  TITANIUM — Continued. 


> 
H 

c/5 

CHARACTER 

| 

A 

x 

X 

AX 

fV 

w 

H 

fc 

I—  I 

SEPARATION. 

o 

1 

W-COMP. 

p-COitP. 

n-coMp. 

p-coup. 

^263.660 

I 

Triple? 

2 

o.  701  wi 

2.530 

5266   141 

6 

Triple 

2 

o  4.08 

i  706 

5282  .  576 

2 

Sextuple? 

n.m.  wj 

W2 

caS^  613 

6 

Triple 

2 

o  4.60 

i  680 

5284  281 

I 

Triple 

n.m. 

5295  .955 

3 

Triple? 

2 

o.  562  wi 

Wj 

2.004 

C2Q7    4.O7 

c 

Triple 

2 

o  ^80 

i   ?86 

^208  672 

4 

Triple 

3 

0.47^ 

I  .602 

Triple 

2 

O   4.CK 

I      7^8 

Enhanced  line 

C2CI      26l 

4 

Triple? 

2 

o  487  wj 

Wi 

I  .  7OI 

t;^6o  782 

sr 

Triple 

3 

0.480 

1.665 

5381    221 

Triple 

2 

O   44O 

I     C2O 

Enhanced  line 

<?oo  203 

•i 

Triple 

I 

O.422 

I  .AC2 

Triple 

2 

o  488 

I    67  <I 

X  by  Fiebig 

CAQA      2l6 

2 

Triple? 

I 

O    7^  Wi 

Wi 

2    ?I7 

X  by  Fiebig 

<4.OQ   823 

7 

Triple 

3 

o.  501 

I  .712 

5418.979 

3 

10  comps. 
Triple 

1,2 

2 

0.538  w3 

O    7<? 

0.346  w2 

1.832 

2    <<CS 

1.178 

Probably  6  »-,  4  p-comps.     En- 
hanced line 

ej.74,   4.26 

Triple 

I 

o  <;i2 

I    7OO 

Blend  makes  measurement  dif- 

6 

Triple 

2 

o  620 

2    066 

ficult 

Ci8l    6l2 

4 

Triple 

2 

O.  <C4Q 

1.827 

5482    078 

4 

? 

n.m. 

n.m. 

Numerous     n-    and     />-comps. 

1:488    *7J. 

Triple? 

I 

o  ^8  Wi 

I     122 

blurred 

2 

O    3QO  W2 

Wa 

I     204. 

K-comps.  fringed 

K 

Triple 

2, 

O    ?I  ? 

I  .  7OO 

EX  I  2    74.1 

12 

Triple 

3 

o.  ?6? 

1.869 

Triple 

2 

o  ^6^ 

I    IQ3 

cci4.   7^3 

12 

Triple 

2 

o  466 

I  .  112 

5565-70° 

8 

Sextuple? 
Triple 

2,2 

2 

0-475  W2 
o  <o8 

0.287 

1-533 

I    lO'C 

0.926 

Triple? 

2 

I  802 

2 

o  676  wi 

Wi 

2    IOO 

Triple 

2 

o  462 

1  .441 

s 

2 

Wi 

I    7<\I 

5689.694 

6 

Sextuple? 

? 

2 

0.515  W2 

W2 

I-59I 
I     IIO 

»-comps.  fringed  and  diffuse 

5708.435 
5712.098 
5714.120 

2 

3 
2 
ft 

Sextuple? 
Sextuple? 
Unaffected 
Triple 

2,1 
2,1 

2 

O  .  846  Wz 
0.790  W3 

o  623 

Q-373 
0.360 

2.596 
2.421 

I   007 

1-145 
1.103 

X  by  Fiebig 

5716.671 
5720.666 

3 
3 

Sextuple? 
Quintuple 

2,2 
1,2 

0.673  w3 

0.473  (i) 

o  ooo  (2) 

0.502 
0.882 

2.059 

1-445 
o.ooo 

1-536 
2-695 

Difficult 

o.476-(i) 

1-454 

Triple 

3 

i  684 

Triple 

2 

o  >;o8 

I.  S42 

5762.479 

i 

Sextuple? 
Triple 

n.m.  ws 

Wj 

I    6OQ 

»-comps.    diffuse,    barely    sep- 
arated 

Triple 

I    7O7 

Sextuple? 

n.m    Viz 

W} 

Triple 

I    807 

5804.479 
5823.910 
5866.675 
5880.490 
5899.518 
5903-555 
5918.773 
5922-334 
5938-035 

594L985 
5953-386 

2 
2 
10 

3 

7 

2 

3 
5 

2 

5 
8 

Triple? 
Sextuple? 
Triple 
Triple 
Triple 
Triple 
Triple 
Triple 
Sextuple? 
Sextuple 

Triple 

2 
2,2 
3 
3 
3 

2 

3 

2 

2,1 
2,2 

3 

0.634  wi 

0.480  W2 

o  674 
0.830 
0.656 
0.876 
0.882 
0.312 
0.840  Wj 
Pair   II,  0.905  (2) 
Pair     1,  0.295  (3) 
0.637 

Wl 

0.268 

0.226 

0.547 

1.882 

I-4I5 
1.958 
2.401 
1.885 

2.SI3 
2.518 
0.890 
2.382 

2.563 
0.836 
1.798 

0.790 

0.641 
1-549 

Red  comp.  strongest? 
p-corap.  scarcely  resolved 

MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  TITANIUM. 

TABLE  2. — MEASUREMENTS  OF  ZEEMAN  EFFECT  FOR  TITANIUM — Continued. 


43 


^ 

> 

H 
V) 

CHARACTER 

| 

^ 

,X 

A> 

A2 

W 

g 

HH 

SEPARATION. 

s 

1 

K-COMP. 

p-COOP. 

»-COMP. 

p-COUP. 

t;o66  .o<< 

7 

Triple 

3 

O    tCQO 

I    6l7 

5978.768 

7 

Triple 

3 

0.533 

1  .491 

5999  .920 

7 

Quadruple? 

2 

o.  823  wi 

W2 

2    286 

6064.  8*»3t 

1 

Triple 

3 

a    I<I 

6085.470 

6091  .395 

4 
6 

Sextuple? 
Triple 

2,2 

3 

I  .  OOI   Wj 

o  670 

0.307 

2.703 

I    8«3 

0.829 

6093  .  030 

T 

Triple 

2 

0.755 

2  .034 

6098.870 

7 

Triple? 

2 

o.  563  Wi 

Wl 

I  .  ei4 

6121.215 

T 

Triple 

2 

0.622 

1.660 

6126  .435 

| 

Septuple? 

2 

o  .  706  Wi 

Wa 

1.881 

w-comps.  fringed.     Probably  3 

6146.445 

T 

Triple 

2 

0.476 

.260 

^-comps. 

I 

Triple 

2 

o  698 

8d< 

6215.630 

^ 

Triple 

3 

0.697 

.804 

6220.700 

7 

Triple 

2 

0.618 

•597 

6221  .552 

T 

Triple 

2 

0.511 

.  320 

6258.322 

TO 

Triple 

2 

0.661 

.688\ 

1 

Red  «-comp.  of  first  line  blended 

6258.927 

17 

Triple 

2 

o  714 

-823[ 

t 

with  violet  comp.  of  second 

6261  .  316 

IO 

Triple 

3 

o  556 

418 

6303-985 
6312.456 

6318.239 

5 
5 

7 

Octuple? 
Octuple? 

Triple 

2,2 
2,2 

2 

0.565  w3 
o  .  766  w3 

0.529 

0-554 
0.463  wi 

.422 
-923 

-335 

1-394 
i  .  162 

w-comps.  very  wide  and  diffuse. 
Probably  at  least  3  pairs 
»-comps.  wide,  not  so  diffuse  as 
6304  .    Probably  3  pairs.    Pos- 
sibly 4  ^-comps. 

6336.329 

^ 

Triple 

2 

0.606 

.510 

6366  .  564 

4 

Triple? 

2 

o  671  Wi 

.6?5 

I 

Sextuple? 

I 

840 

Xby  Fiebig 

6491  .  800 

5 

Triple 

2 

O    7<2 

.785 

Enhanced  line  Tit  Not  given  by 

6497  840 

2 

Triple 

2 

2  86? 

Fiebig  for  arc 

6508.380 

2 

? 

T 

I  318  Ws 

3.112 

w-comps.  very  wide  and  diffuse 

6513.300 

7 

Triple 

2 

o.  610 

1.438 

Enhanced  line  Tif   Not  given  by 

6546.479 

X 

Triple 

2 

O   4<Q 

i  .071 

Fiebig  for  arc 

6554.470 

9 

Triple 

J 

o.  795 

1.851 

6trc6   308 

Triple 

3 

o  896 

2    085 

6ct;o  8is 

2 

Triple 

7 

i   ?8o 

Ti?    Not  given  by  Fiebig 

6c6<;  783 

Sextuple' 

2    ^2O 

6575  .437 

2 

Triple? 

I- 

1.480 

X  by  Fiebig 

6S99-353 
6606.160 
6666.714 
6667  998 

r 
2 

2 

Triple 
Quadruple? 
Triple? 
Triple? 

3 

2 

I 

0.711 
0.881  wi 

0.753  Wi 

Wl 
Wi 

1.633 

2.019 

1.694 

Ti?    Not  given  by  Fiebig 
X  by  Fiebig.    Blended  with  flut- 

6716.922 
6717.964 
6743-381 

2 
2 

6 

Triple 
Triple 
Triple 

I 
il 
2 

0.772 
0.862 
0.759 

1  .711 

1.910] 

1  .669 

ing  lines 

TYPES  OF  SEPARATION. 

The  number  of  lines  for  each  type  of  separation,  including  both  the  clear  and  the  doubtful  cases,  is 
given  in  Table  3.  For  the  quadruplets,  sextuplets,  and  septuplets,  the  questioned  lines  greatly  out- 
number the  clear  cases.  For  example,  iron  shows  only  two  clear  septuplets  and  titanium  two  clear  quad- 
ruplets. A  strong  field  will  probably  show  that  these  doubtful  lines  have  usually  been  correctly  classi- 
fied as  to  number  of  components,  but  actual  measurements  for  the  unresolved  components  are  at  present 
lacking. 

TABLE  3. — SUMMARY  OF  TYPES  or  SEPARATION. 


SEPARATION. 

IRON. 

TITANIUM. 

Unaffected    

4. 

Triple 

2Q7 

Quadruple  .  . 

AQ 

28 

7 

Sextuple  .   .  . 

118 

77 

Septuple  

VI 

12 

Octuple 

6 

9  components 

10  components  

7 

7 

ii  components  

2 

2 

12  components 

4 

2 

13  components  

2 

o 

Unclassified  . 

10 

16 

Total 

662 

Atfl 

i.  UNAFFECTED  LINES. 

A  number  of  lines  in  each  spectrum  show  no  tendency  toward  separation  or  even  widening  by  a 
magnetic  field  as  high  as  20,000  gausses.  The  light  giving  such  lines  is  unpolarized  so  that  a  single 
sharp  line  appears  in  the  magnetic  field  spectrum,  whatever  the  optical  system  may  be.  The  num- 
ber of  these  lines  is  not  large,  the  undoubted  cases  being  as  herewith : 


IKON. 

TITANIUM. 

^3746.  058 
3767.341 
3773-803 

3786  820 

\38so.n8 

SI23-899 
5434.740 

\4295.Qi4 
5222.849 
5714.120 

2.  TRIPLETS. 

The  number  of  triplets  is  larger  than  that  of  any  other  one  type,  the  number  of  clear  cases,  i.e.,  those 
whose  components  show  no  widening  which  would  indicate  that  they  are  compound,  being  297  for  iron 
and  247  for  titanium.  The  relation  of  the  separation  of  these  to  the  "normal  interval"  will  be  treated 
in  another  part  of  this  paper. 

A  rather  curious  mistake  has  found  its  way  into  the  literature  based  on  some  lines  in  the  iron  spec- 
trum. Becquerel  and  Deslandres  in  their  first  publication  (9)  gave  X 3865.674  as  an  "inverted  triplet," 
having  but  a  single  w-component  and  two  /^-components.  This  evidently  arose  from  under-exposure  of  their 
photographs  for  the  «-component,  as  in  their  next  paper  (10)  they  gave  the  correct  character  of  this  line, 
44 


TYPES  OF  SEPARATION.  45 

it  being  a  quintuplet  with  three  n-  and  two  /(-components,  the  central  w-component  being  strongest. 
Reese  (12)  made  the  same  error  concerning  both  this  line  and  X  3643.469,  together  with  another  farther 
to  the  violet.  Kent  (13)  followed  with  a  publication  in  which  the  lines  are  correctly  described.  Cotton  (i«) 
calls  attention  to  the  confusion  which  has  come  about  and  gives  the  correct  structure.  Runge  (»*)  cites 
the  first  paper  of  Becquerel  and  Deslandres  and  that  of  Reese  concerning  the  inverted  triplet,  without 
noting  that  the  error  had  been  corrected  in  each  case  by  later  publications,  though  Runge  later  (2^)  repro- 
duced the  diagram  of  Becquerel  and  Deslandres  from  their  second  paper,  in  which  the  correct  structure 
of  these  lines  is  given.  Other  works  on  spectroscopy  speak  of  the  inverted  triplet,  the  basis  for  this 
being  the  publications  which  have  been  mentioned.  No  real  case  of  the  inverted  triplet  has  presented 
itself  in  the  iron  or  titanium  spectrum,  nor,  so  far  as  the  author  is  aware,  does  such  a  type  exist  in  any  other 
spectrum.  Apparent  examples  of  such  inversion  are  likely  to  appear  on  plates  not  fully  exposed,  since 
some  quintuplets,  \4464.6i7  of  titanium  for  example,  show  a  central  w-component  very  much  stronger 
than  the  two  outer  ones,  so  that  the  central  component  may  easily  appear  alone. 

The  tendency  of  Zeeman  components  to  follow  the  appearance  of  the  no-field  line  as  regards  sharp- 
ness or  diffuseness  frequently  makes  it  difficult  to  judge  whether  a  line  is  a  true  triplet  or  not.  If  the 
lack  of  sharpness  is  not  due  to  the  character  of  the  no-field  line,  a  doubtful  triplet  may  be  (i)  a  quadruplet 
if  the  diffuse  /(-component  is  really  double,  (2)  a  sextuplet  if  each  of  the  three  widened  n-  and  ^-com- 
ponents are  double,  (3)  a  septuple!  if  the  two  w-components  are  double  and  the  /(-component  has  three 
close  constituents.  Still  higher  separations  for  doubtful  triplets  are  not  impossible,  but  probably  there 
are  very  few  such.  The  criterion  for  distinguishing  between  these  possible  types  is  given  on  p.  19. 

3.  QUADRUPLETS. 

The  unquestioned  quadruplet  is  somewhat  rare.  The  great  majority  of  lines  having  two  n-  and  two 
/(-components  have  their  w-components  widened  to  some  extent  and  are  usually  classed  as  doubtful 
sextuplets,  since  so  many  of  these  have  been  resolved  by  the  strongest  fields  used  that  it  seems  probable 
that  a  still  stronger  field  would  show  four  w-components  for  such  lines  in  every  case.  Occasionally,  how- 
ever, the  two  w-components  are  sharp.  The  relative  separation  of  n-  and  /(-components  varies  greatly 
for  different  lines,  but  the  /(-components  are  almost  always  closer  together.  The  most  decided  excep- 
tion is  the  titanium  line  X  4398.460,  apparently  a  quadruplet,  whose  w-components  show  only  two-thirds 
the  separation  of  the  p  pair. 

4.  QUINTUPLETS. 

The  quintuplet  appears  least  often  of  any  of  the  less  complex  types.  As  a  rule  this  separation  gives 
three  n-  and  two  /(-components,  the  distance  between  the  /(-components  being  the  same  as  between  the 
outer  w-components.  The  central  w-component  is  the  strongest  of  the  three,  and  the  effect  when  the  light 
is  observed  at  right  angles  to  the  lines  of  force  without  a  Nicol  prism  is  to  give  a  triplet,  the  components 
of  which  are  of  about  equal  intensity,  caused  by  the  superposition  of  the  p  doublet  on  the  two  outer 
w-components.  Good  examples  are  XX3733-469  and  3865.674  of  iron,  and  4291.114  of  titanium.  The 
first  two  were  originally  mistaken  for  "inverted  triplets"  on  account  of  the  strong  central  «-component. 
Dissymmetry  is  sometimes  present,  as  in  X  5455.834  of  iron.  A  different  type  is  presented  in  X  4710.368 
of  titanium,  which  shows  four  w-components  and  a  single  sharp  /(-component.  No  similar  line  has  been 
observed  in  either  of  these  spectra. 

5.  SEXTUPLETS. 

This  type  usually  has  the  two  pairs  of  w-components  of  equal  intensity,  shown  by  a  uniform  widening 
in  cases  where  the  pairs  are  blended.  As  has  been  previously  noted,  the  sextuplet  is  a  very  common 


46          INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

type,  a  great  number  of  lines  being  classed  as  probable  sextuplets  which  show  as  diffuse  triplets  with  this 
field.  A  field  of  considerably  greater  intensity  will  probably  show  these  to  be  similar  to  most  of  the  sex- 
tuplets which  are  fully  resolved  here.  The  /'-components  of  those  sextuplets  which  have  been  measured 
are  usually  rather  narrowly  separated,  while  the  two  pairs  of  w-components  are  frequently  almost  blended. 

6.  SEPTUPLETS. 

The  prevailing  type  of  septuplet  has  four  n-  and  three  ^-components,  the  two  pairs  of  w-components 
not  usually  being  of  the  same  intensity.  When  blended,  the  M-components  give  the  "fringed"  appear- 
ance often  noted  in  the  "Remarks"  column,  in  which  case  the  weaker  pair  may  be  either  inside  or 
outside.  When  the  ^-components  are  not  resolved,  it  is  often  difficult  to  distinguish  this  type  from  the 
sextuplet,  the  difference  depending  on  the  existence  of  a  central  maximum  in  the  widened  ^-component. 

7.  OCTUPLETS. 

The  typical  octuplet  has  five  n-  and  three  />-components,  equally  spaced.  The  outer  w-components 
are  usually  the  stronger  and  the  central  one  quite  weak,  so  that  when  the  three  />-components,  if  the 
central  one  is  the  stronger,  are  superposed,  as  when  the  light  is  viewed  across  the  lines  of  force  without  a 
Nicol,  the  effect  is  to  show  five  components  of  about  equal  intensity.  Examples  of  such  lines  are 
XX 3743. 508,  3788.046,  5497.735,  of  iron,  and  4281.530,  4527.490,  4544.864,  of  titanium.  The  last  two 
were  given  as  septuple ts  in  my  former  paper  (51)  on  account  of  the  weakness  of  the  central  «-com- 
ponent.  Another  arrangement  is  presented  by  the  titanium  line  X43o8.o8i  which  has  three  pairs  of 
^-components  and  two  ^-components. 

8.  NONETS. 

Good  examples  of  lines  having  nine  components  are  found  in XX  3840.580,  4233.772  of  iron,  and  4471 .408 
4489.262,  4629.521  of  titanium.  These  have  each  three  pairs  of  w-components,  the  innermost  pair  being 
strongest,  and  three  /'-components.  The  type  is  probably  rather  common  in  both  spectra,  since  many 
lines  classed  as  doubtful  septuplets  may  have  a  weak  outer  pair  of  ^-components,  making  a  total  of  nine. 

9.  MORE  COMPLEX  TYPES. 

Lines  having  ten  components  are  represented  by  XX44I7-884,  4471.017,  and  5025.027  of  titanium. 
These  are  made  up  in  each  case  of  three  pairs  of  n-  and  two  pairs  of  ^-components.  Eleven  components 
are  shown  by  X  3888.671  of  iron,  which  has  a  central  w-component  in  addition  to  the  pairs  of  the  ten- 
component  type.  Several  good  examples  of  twelve-component  lines  are  given  byXX3722-729,  3872.639, 
5447.130  of  iron  and  4289.237  of  titanium.  These  are  all  of  similar  structure,  having  four  pairs  of 
w-components,  the  two  inner  pairs  having  the  same  separation  as  the  two  pairs  of  ^-components.  While 
twelve  is  the  highest  number  of  components  which  is  measurable  on  my  plates,  the  iron  lines  XX 4005. 408 
and  4132.235  are  given  as  probably  having  thirteen  components  each.  Five  ^-components  are  almost 
resolved  in  each  case  and  the  wide  inner  fringes  for  the  «-components  are  estimated  to  consist  of  four 
pairs.  Many  of  the  lines  whose  type  is  questioned  without  attempt  to  estimate  the  number  of  compo- 
nents have  probably  as  many  as  the  most  complex  of  those  measured,  and  some  of  them  possibly  more. 

Good  examples  of  almost  all  of  these  types  of  separation  are  present  among  the  violet  iron  lines  shown 
in  Plate  III,  which  has  the  advantage  of  showing  the  n-  and  ^-components  both  separate  and  in  combi- 
nation, the  latter  spectrum  being  taken  at  right  angles  to  the  force-lines  without  the  use  of  a  Nicol  prism. 
Polarization  by  the  grating  reduced  the  intensity  of  the  ^-component  for  this  region  of  the  spectrum, 
as  is  shown  by  the  relative  weakness  of  the  central  component  of  triplets  in  the  spectra  lettered  b,  for 
which  the  Nicol  prism  was  not  used. 


RELATION  OF  SEPARATIONS  TO  THE  NORMAL  INTERVAL, 
i.  SUMMARIES  FOR  VARIOUS  TYPES. 

The  study  of  how  generally  the  separations  observed  show  a  simple  relation  to  the  fundamental 
interval,  the  theory  of  which  was  summarized  on  p.  4,  has  been  gone  into  in  some  detail.  The  relation 

e     H 
a=  — •— 
m   4TW 

gives  a  value  for  a  of  0.753  f°r  H  =  16,000,  and  of  0.812  for  H=  17,500,  if  e/m  be  taken  equal  to  1.75  X  io7. 
The  "normal  triplets"  for  iron  and  titanium,  with  the  standard  field-strengths  used  in  this  work,  should 
accordingly  show  values  of  AX/X2  for  the  distance  between  the  side  components  of  about  1.500  and  1.600 
respectively. 

In  the  following  summaries  an  attempt  has  been  made  to  show  to  what  extent  the  separations  for 
various  classes  of  lines  may  be  considered  as  multiples  of  the  interval  a.  In  Table  4  the  clear  triplets 
for  iron  and  titanium  are  thus  classified,  those  triplets  given  in  Tables  i  and  2  as  doubtful  not  being 
included.  The  allowable  deviation  for  any  line  from  the  exact  multiple  was  estimated  as  closely  as  pos- 
sible according  to  the  weight  of  the  measurement,  knowing  the  probable  error  for  each  weight.  Lines 
not  falling  into  any  class  are  placed  in  the  "Odd"  column.  In  the  case  of  titanium  a  large  proportion 
of  such  lines  appeared  to  be  definite  odd  multiples  of  a/4,  while  the  regular  classes  consider  only  multiples 
of  a/2.  As  in  all  of  the  following  work  relating  to  the  interval  a,  greater  field  strength  is  desirable,  as  the 
accuracy  of  the  classification  increases  with  the  numerical  value  of  a;  but  Table  4  shows  in  a  general  way 
how  the  magnitudes  of  the  separations  may  be  grouped. 

TABLE  4. — SEPARATION  OF  TRIPLETS  AS  RELATED  TO  THE  NORMAL  INTERVAL  a. 


a 

30/2 

2(1 

5a/2 

3<* 

?fl/2 

4<i 

5* 

6a 

ODD 

REMARKS. 

Element,  Iron: 
Wt.  3  

o 

e 

2? 

17 

11 

6 

4 

7 

4 

16 

Wt.  2.... 

2 

IO 

27 

27 

2 

2 

o 

o 

20 

Wt.  i  

I 

IO 

II 

IO 

a 

I 

o 

o 

6 

Total  

a 

21 

54 

55 

72 

II 

7 

3 

4 

42 

Element,  Titanium: 
Wt.  i... 

e 

4.O 

i  <; 

14, 

I 

2 

76 

Wt.  2  

c 

e 

27 

i-j 

2 

2 

i 

o 

o 

21 

90/4,  32  lines 
"  Odd  "   includes   ?fl/4    7  lines' 

Wt.  i  

2 

I 

6 

2 

I 

o 

o 

o 

o 

o 

ga/4,  8  lines 

Total 

7 

7? 

-an 

17 

O7 

The  relation  of  the  separation  to  the  normal  interval  was  also  studied  for  those  lines  which  appear 
on  my  plates  as  quadruplets  with  components  in  many  cases  diffuse,  indicating  a  compound  structure. 
The  two  ^-components  are  usually  fairly  sharp,  but  the  re-components  are  often  formed  of  two  or  more 
pairs  blended.  Close  agreement  with  exact  multiples  of  the  normal  interval  can  not  be  expected  for 
lines  of  this  class,  but  in  the  majority  of  cases  the  distance  between  the  components  of  the  n  and  p  pairs 
could  be  expressed  as  multiples  of  a  or  a/2  closely  enough  to  show  a  real  relation;  66  lines  of  iron  and 

47 


INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 


49  of  titanium  were  thus  treated,  and  80  per  cent  of  the  former  and  75  per  cent  of  the  latter  were  found 
to  show  separations  related  to  a  in  this  way.  Table  5  gives  the  number  of  lines  corresponding  to  each 
ratio  of  separation  for  n-  and  p-components  when  these  could  be  expressed  in  terms  of  a  or  a/ 2. 

TABLE  5. — SEPARATIONS  OF  APPARENT  QUADRUPLETS  IN  TERMS  OF  NORMAL  INTERVAL. 


SEPARATION. 

No.  OF  LINES. 

SEPARATION. 

No.  OF  LINES. 

H-COMP. 

^-COMP. 

IRON. 

TITANIUM. 

n-coMp. 

/l-COMP. 

RATIO. 

IRON. 

TITANIUM. 

M 

3d 

i: 

2 

3 

5<J/2 

a 

5:2 

3 

5»/2 

SI/2 

i: 

I 

70/2 

a 

7:2 

M 

a 

2: 

8 

7 

a 

30/2 

2:3 

60 

3« 

2: 

2 

M 

30/2 

4=3 

30 

30/2 

2: 

4 

2 

Si/2 

30/2 

5:3 

30 

a 

3  = 

18 

6 

70/2 

3^/2 

7:3 

ga/2 

30/2 

3  = 

i 

SO/2 

M 

5=4 

5« 

a 

5  = 

i 

n.m. 

30/2 

i 

3 

3<» 

M 

3=2 

S 

i 

n.m. 

M 

... 

4 

6 

30/2 

a 

3:2 

i 

n.m. 

30 

... 

I 

•• 

Fourteen  lines  of  iron  and  13  of  titanium  gave  separations  not  to  be  expressed  in  terms  of  a/2,  but  most 
of  these  showed  a  simple  ratio  between  the  n  and  p  separations.  For  iron,  2  lines  showed  a  ratio  of  i :  i, 
6  lines  of  2:1,  2  lines  of  3  :i,  2  lines  of  4:1.  The  odd  lines  of  titanium  had  among  them  5  of  ratio  2:1, 
and  i  of  ratio  4:1. 

The  more  complex  lines,  so  far  as  they  were  resolved  by  the  field  employed,  have  been  arranged  in 
the  following  summary.  In  each  case,  below  the  wave-length,  the  first  column  gives  the  interval  in 
terms  of  a  from  either  the  red  or  the  violet  component  to  the  center  of  separation.  (The  triplets  and 
quadruplets  in  Tables  4  and  5  have  their  separations  given  as  the  total  distance  from  the  red  to  the  violet 
component.)  The  second  column  shows  whether  it  is  the  n-  or  ^-component  which  has  this  separation. 
If  both  letters  are  present  for  a  given  interval,  there  is  a  superposition  of  components  having  the  two 
polarizations.  The  last  column  gives  the  ratio  of  the  successive  intervals. 


Iron: 


X  3718.  554 

±S<J/4   »    2 

50/8  p  i 
o      no 

Titanium: 


<       3760.679 
(_     3814-671 


X42QI.H4 
±30/2  n,p  — 
o        n     — 


QUINTUPLETS. 

3865.674] 

5455  .  834  >  have  the  arrangement 

5603.186) 


, 
i 


X44&4.6I7 

±70/4  n  2 

70/8  p  i 

o        no 


X  4710.368 

±40/3  n  8 

a/2  n  3 

o      p  o 


X572O.666 

±30/2  n,p  — 

o        n     — 


Iron: 


Titanium 


*  3774-971 
±50/2  n  10 
53/4  «     5 
a      p    4 

:   X  3982.  142 

±31/2  n  3 
a      p  2 
a/2  n  i 

X  4109.  953 
±30/2  n 
30/4  «,£ 

X4422 
2          ±3a/2 

I                      0 

0/2 

X  4321.  119 
±2ia/8  » 
7a/8  n,p 

SEXTUPLETS 
741          X4447. 
n  3         ±2a 
p  2            33/2 
n  i              a 

X  4640.119 
3      ±50/2  n  5 
i          33/2  n  3 

O         #1 

892 

n  4 
»  3 

/>    2 

X  472 

±3<»/2 

90/8 

W/8 

*  4872.  332 

±33         »         2 
33/2    »,/>    I 

X  6213.644 
±33      n  6 
33/2  w  3 
o      />  2 

169       X  4805 
n  3       ±30/2 

/>    2                 3 
»    I                  3/2 

.28S 

»  3 

n  2 
<•  i 

X  633  7.  048 
±33      n  6 
30/2  n  3 

3         />    J 

±30/2  n  3 

3         />    2 
3/2    »    I 

X  4302.  085 
±20      n  8 
3"/4  P  3 

O/2   »    2 

2.797 
H   12 

#     9 
»    i 

X  4798 

±3a/2 
a 

3/2 

SEPTUPLETS. 


Iron: 


X  4009. 864 
±20  n  8 

o  n  4 
30/4  #  3 

0       ^9 


X  4191. 595 
±20      n     2 
a      n,p  i 
o      p     o 


X  4352. 908 

±(20      n  4)? 

30/2  n  3 

a/2  p  i 

o      p  o 


X 5079. 921 

±23   n  2 

a  n?,p  i 
op        o 


Titanium: 


X 4298. 828 

±3        »  2 

3/2    H,p  I 

o      p  o 


RELATION  OF  SEPARATIONS  TO  THE  NORMAL  INTERVAL. 


49 


Iron:    X  3 748. 408 
±30/2  n      3 
a      n      2 

0/2    »,/>?! 

o      />      o 


OCTUPLETS. 

Iron:    \3743-  5°8          X  3788.  046          X  4859.  928              X  5497.  735 
±20  n         2          ±20  n      2        ±(30      n      2)?       ±30      n      2 
a  n,p      i               a  n,p  i              30/2  n,p  i              30/2  n,p  i 
o  n,p      o               o  n,p  o               o      n,p  o               o      »,^>  o 

Titanium:     X  4281.  530           X  4308.081           X  4527.  490          X  4544.  864          X  4590.  126 
±34      n      2       ±20      «  8          ±20  «      2          ±20  »      2          ±30/2  n  12 
30/2  «,^  i          30/2  »  6               a  «,/>  i               a  «,^  i               a      n    8 
o      n,p  o           a      n  4               o  »,£  o               o  n,p  o             70/8  p    7 

30/4      £      A                                                                                                                                                             fit1)     «          yl 

NONETS. 

X  3840  .  580 

X  4233.  772 

X  5405.  989              Titanium:    X447i.4o8 

X  4489  .  262 

X  4629.  521 

±30/2  n 

3 

±30  n 

3 

±(30/2  » 

3)? 

±210/8  »  7 

±210/8  n  7 

±50/2  n  5 

a      n 

2 

20  n 

2 

a      n 

2 

150/8  n  5 

150/8  n  5 

30/2  »  3 

a/2  n,p 

I 

a  n,p 

I 

a/2  n,p 

I 

9"/8  n  3 

90/8  n  3 

a      #2 

o      p 

O 

o  p 

O 

o       p 

O 

30/4  p  2 

30/4  p  2 

0/2  n  i 

o      p  o 

o      p  o 

O        p  O 

TEN-COMPONENT  LINES. 


Titanium:    X  441 7. 884 

±  ?      n  ? 

a      n  8 

30/4  />  6 

30/8  »  3 

a/4  p  2 


X 4471. 017 
±90/4  TC       6 

3«  /4£  4 
90/8  n,p?  3 
30/8  »  i 


X  5025. 027 

±30/2    »  24(5) 

50/4    p  20(4) 

o        n  16(3) 

50/8    p  10(2) 

50/16  n    5(1) 


The  numbers  in  parentheses  for  X  5025.027  give  a  simpler  relation  between  the  intervals  than  the  exact 
ratio  of  the  multiples  of  parts  of  a.  Another  probable  ten-component  line  13X3982.630,  for  which  the 
measurements  are  poor.  Its  w-components  are  in  the  ratio  5:3:1. 


Iron:     X  3888. 671 

±30/2  »        3 

o      n,p    2 

a/2  n,p?  i 

o      n       o 


ELEVEN-COMPONENT   LINES. 

X  4871. 512 
±(30/2  n        3)? 
a      n,p     2 
0/2  nf,p  i 
o      p       o 


Titanium :    X  3930 .022 

±90/4  n,p    3 

30/2  »,/>?  2 

30/4  n       i 

o      »       o 


X  487 1.5 1 2  has  its  w-components  blended,  but  the  structure  indicates  the  above  arrangement. 
The  titanium  line  X392I.563  has  probably  the  same  structure  as  X393O.O22.     The  w-components 
have  the  ratio  3:2:1:0,  but  the  measurements  are  not  good  enough  to  be  sure  of  the  relation  to  a. 


Iron:    X 3722. 729 

±20      n      4 

30/2  »      3 

a      n,p  2 

a/ 2  »,/>?! 


TWELVE-COMPONENT  LINES. 
X  3872. 639         X  5447. 130 
±20       n      4       ±20       n      4 
30/2  n      3          30/2  n      3 
a      n,p  2  a      n,p  2 

a/2  n,pfi  a  1 2  n,p  i 


Titanium: 


X 4289. 237 
±20      n     4 

30/2  »  3 
a  n,p  2 
0/2  n,p  i 


2.  DISCUSSION  OF  RELATIONS  TO  NORMAL  INTERVAL. 

It  is  shown  in  Table  4  that  for  iron  two-thirds  and  for  titanium  over  one-half  of  the  clear  triplets 
are  separated  by  the  intervals  2a,  50/2  and  30.  For  both  elements,  however,  a  very  large  majority  have 
separations  of  this  order  of  magnitude,  since  almost  all  of  the  lines  classified  as  "odd"  give  intervals 
within  this  range,  the  numbers  corresponding  to  7*1/4  and  90/4  of  weights  i  and  2  being  given  for  titanium 
in  the  "Remarks"  column.  A  more  precise  classification,  in  which  smaller  fractional  parts  of  a  can  be 
used,  must  await  an  investigation  with  greater  field-strength,  which  will  also  decide  the  structure  of 
most  of  the  doubtful  triplets,  the  separation  of  which  is  not  included  in  any  of  these  summaries. 

Table  5  shows  how  generally  the  separations  of  those  lines  showing  two  n-  and  two  /'-components 
can  be  expressed  in  terms  of  the  interval  a,  also  the  wide  variety  of  separations  which  prevails.    The  ratios 
of  2 :  i  and  3 :  i  predominate  for  both  elements.    As  has  been  previously  noted,  the  /'-components  almost 
always  show  the  narrower  separation. 
4 


50          INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

The  ease  with  which  the  separations  of  the  complex  lines  both  in  iron  and  titanium  can  be  expressed 
in  terms  of  a  affords  a  confirmation  of  Runge's  law,  since  failure  to  give  approximation  to  exact  multiples 
of  a  appears  to  occur  only  in  the  case  of  measurements  of  small  weight.  It  has  been  necessary  only  in 
a  very  few  cases  to  use  multiples  of  any  quantity  smaller  than  a/4,  so  that  errors  of  measurement  are 
seldom  large  enough  to  influence  the  ratios  found.  This  question  will  become  of  more  importance  when 
very  close  components  are  resolved  by  a  stronger  field. 

The  presence  of  "magnetic  duplicates,"  lines  exactly  similar  in  structure,  with  the  same  intervals 
between  components,  furnishes  a  means  of  selecting  lines  which  may  be  connected  by  series  relations. 
Such  duplicates  occur  for  almost  every  type  of  separation.  Six  quintuplets  of  iron  and  two  of  titanium 
show  the  same  structure  and  intervals.  These  are  XX 3 733 .469,  3760.679,  3814.671,  3865.674,  5455.834, 
5603.186  of  iron  and  4291.114,  5720.666  of  titanium.  Several  types  of  sextuplets  appear.  The  red  lines 
of  ironXX62i3-644  and  6337.048  are  duplicates,  also  the  titanium  lines  XX3982.I42, 4798.169,  and  5491.985. 
Duplicate  septuplets  of  iron  areXX4i9i.s85  and  5079.921.  The  only  titanium  septuplet  fully  resolved, 
X  4298.828,  has  the  same  structure.  The  four  iron  octuplets  are  of  the  same  appearance  but  have  dif- 
ferent spacing,  XX3743-5o8  and  3788.046  being  alike,  as  are  probably  also  XX4859-928  and  5497.735, 
though  the  former  was  not  fully  measurable.  The  blue  octuplets  of  titanium  XX452749O  and  4544.864 
are  also  duplicates.  The  iron  nine-component  lines  XX 3 748. 408  and  3840.580  are  alike,  and  X  5405. 989 
has  probably  the  same  intervals.  Another  spacing  is  shown  by  the  titanium  duplicates  XX  447 1 .408  and 
4489.262.  The  lines  of  iron  which  probably  have  ten  components  are  not  fully  resolved,  while  the  three 
titanium  lines  show  diverse  arrangements.  Perhaps  the  finest  examples  of  spacing  in  multiples  of  a  are 
the  twelve-component  lines  XX3722.729,  3872.639,  5447.130  of  iron,  which  are  exact  duplicates,  while 
X4289-237  of  titanium  is  in  all  respects  similar. 


POSSIBLE  RELATIONS  BETWEEN  LINES  AS  INDICATED  BY  THE  ZEEMAN  EFFECT. 

It  is  hoped  that  the  measurements  presented  in  this  paper,  especially  the  summary  of  complex  sepa- 
rations given  on  pp.  48  and  49,  may  eventually  aid  in  finding  definite  relations  among  the  lines  of  these 
spectra.  At  present,  nothing  conclusive  along  this  line  is  to  be  offered.  Numerous  cases  of  magnetic 
duplicates  have  been  shown  to  exist  in  both  spectra.  Such  lines,  especially  if  they  are  in  the  same  part 
of  the  spectrum,  are  often  affected  in  the  same  way  as  to  change  of  intensity  in  various  light  sources 
and  show  a  similar  magnitude  of  displacement  by  pressure.  The  same  vibrating  particle  probably  pro- 
duces them. 

The  differences  in  wave-number  (i/X)  have  been  formed  for  the  various  pairs  of  magnetic  duplicates. 
Only  one  case  was  found  where  two  pairs  of  magnetic  duplicates  have  the  same  difference  of  wave-number. 
The  iron  octuplets  XX 3 743. 508  and  3788.046  have  exactly  the  same  difference  in  wave-number  (314)  as 
the  sextuplets  XX63I3.644  and  6337.048.  No  case  was  found  where  two  pairs  of  magnetic  duplicates 
of  the  same  type  have  the  same  difference,  though  this  was  tried  wherever  promising,  both  between  known 
duplicates  and  as  a  means  of  finding  new  pairs.  The  differences  between  duplicates  were  found  to  vary 
greatly  for  each  element  and  to  bear  no  simple  relation  to  one  another;  so  that  as  yet  no  clue  has  been 
found  which  will  serve  in  building  up  series  relations. 


IRON. 

TITANIUM. 

*37i8.  554 
3760.679 
3892.069 

3952-754 
4878.407 

5324-373 
5455-834 

X  3998.  790 
4009.807 
4298.828 
4645.368 
4997  .  283 
5219-875 
5903-S55 

CASES  OF  DISSYMMETRY. 

There  are  but  few  striking  examples  of  dissymmetry  in  the  iron  and  titanium  spectra,  either  in  spacing 
of  the  components  or  in  the  intensities  of  the  violet  and  red  components.  However,  fourteen  lines  show- 
ing distinct  dissymmetry  may  be  listed  as  shown  herewith: 

The  nature  of  the  dissymmetry  is  covered  in  each  case  in  the 
"Remarks"  column.  Several  triplets  show  either  the  red  or  the  violet 
component  decidedly  stronger.  Quintuplets  are  likely  to  show  irregular 
spacing  or  intensity,  or  both,  as  in  the  cases  of  XX 37 18.554,  3760.679  and 
5455.834,  of  iron.  The  last  line  has  its  central  w-component  moved  dis- 
tinctly to  the  red  from  the  position  of  the  no-field  line  (see  Plate  IV). 
The  titanium  septuplet  X 4298.828  shows  three  /(-components,  the  interval 
between  the  central  and  violet  components  being  about  two-thirds  that 

between  the  central  and  red.    This  line  appears  on  Plate  V.    Several  of  the  other  lines  are  of  complex 
type  and  highly  unsymmetrical. 

The  plates  taken  in  this  investigation  are  for  the  most  part  not  suitable  for  the  detection  of  a  differ- 
ence in  the  spacing  from  the  central  line  of  the  violet  and  red  component  of  triplets,  since  a  Nicol  was 
almost  always  used  to  separate  the  n-  and  ^-components.  However,  two  of  the  best  plates  in  the  set 
were  taken  without  a  Nicol  for  the  iron  spectrum  in  the  blue  and  violet  regions  and  include  most  of  the 
lines  mentioned  by  Zeeman  (30)  as  showing  a  difference  in  the  intensity  or  in  the  spacing  of  the  violet  and 
red  components.  These  plates  were  taken  with  a  field-strength  of  19,500  gausses.  A  set  of  measure- 
ments was  made  for  the  sharpest  triplets  occurring  in  this  region  to  test  the  question  of  a  difference  in 
the  spacing  of  the  violet  and  red  components  from  the  central  line.  The  method  was  to  make  settings 
successively  on  the  violet,  central,  and  red  components,  and  then  repeat  in  the  inverse  direction,  con- 
tinuing until  four  sets  of  readings  were  obtained  from  which  the  mean  distance  to  each  side  component 
was  computed.  The  measurements  given  in  Table  6  are  the  mean  of  two  independent  sets  taken  in  this 
way,  which  in  general  agreed  closely.  Thus  each  value  of  AX  is  the  mean  of  eight  determinations  of  the 
interval  in  question.  The  values  of  AX  are  not  reduced  to  the  standard  field.  Differences  in  favor  of  the 
violet  interval  are  +,  those  in  favor  of  the  red  interval  — . 

TABLE  6. — SPACING  OF  VIOLET  AND  RED  COMPONENTS  OF  IRON  TRIPLETS  FROM  THE  CENTRAL  COMPONENT. 


AX 

AX 

X 

CENTER  TO 

CENTER  TO 

DIFFERENCE. 

X 

CENTER  TO 

CENTER  TO 

DDJFERENCE. 

VIOLET. 

RED. 

VIOLET. 

RED. 

3687.610 

0.204 

o.  198 

+0.006 

3920.410 

0.231 

0.218 

+0.013 

3709.389 

O.2OO 

O.2OI 

—  o.ooi 

3923.054 

0.228 

0.223 

+  0.005 

3758-37S 

0.179 

0.165 

+0.014 

3928.075 

0.227 

0.223 

+0.004 

3763.945 

0.148 

0.136 

+  O.OI2 

3930.450 

0.230 

O.22I 

+0.009 

3765.689 

0-153 

0.142 

+  O.OII 

3997-547 

0.173 

0.168 

+0.005 

3798.655 

O.2I2 

O.2O9 

+0.003 

4063  .  759 

0.179 

0.177 

+  O.OO2 

3799.693 

0.213 

O.2II 

+  O.OO2 

4236.112 

0.285 

0.280 

+  0.005 

3827.980 

0.153 

0.139 

+0.014 

4260.640 

0.278 

0.272 

+  0.006 

3856.524 

0.222 

0.213 

+0.009 

427I-934 

0.218 

0.216 

+  O.OO2 

3860.055 

O.2I7 

O.2I9 

—  O.O02 

4308.081 

O.2OO 

0.194 

+  0.006 

3886.434 

o.  225 

0.214 

+  O.OII 

432S-939 

0.170 

0.161 

+  0.009 

3895-803 

0.223 

0.223 

o.ooo 

4383.720 

O.2I7 

O.2IO 

+  0.007 

3899.850 

0.225 

O.22I 

+0.004 

4404.927 

0.212 

0.208 

+  0.004 

52  INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 

These  measurements  are  intended  only  as  a  preliminary  test  of  the  reality  of  the  difference  in  triplet 
spacings.  The  evidence,  however,  points  strongly  to  the  existence  of  a  true  difference  for  many,  if  not 
all  triplets.  Only  3  out  of  26  lines  fail  to  show  a  larger  interval  for  the  violet  component.  Although  the 
settings  on  a  component  seldom  show  a  range  greater  than  0.004  A,  which  would  indicate  a  very  small 
probable  error  in  the  mean  of  8  determinations,  it  is  likely  that  the  actual  probable  error  of  the  indi- 
vidual differences  shown  in  Table  6  may  amount  to  0.003  or  0-004  A  as  a  result  of  systematic  errors  in 
the  settings  due  to  the  character  of  the  lines.  The  mean  of  all  the  differences  is  +  0.006  A,  with  a  calcu- 
lated probable  error  of  ±  o.ooi  A,  which  can  scarcely  leave  any  doubt  as  to  the  reality  of  the  difference. 

The  measurements  show  that  the  magnitude  of  the  difference  can  hardly  be  the  same  for  all  of  the 
lines.  The  true  probable  error  will  then  be  somewhat  smaller  than  that  given  above,  which  would  only 
make  the  evidence  for  the  reality  of  the  dissymmetry  predicted  by  Voigt  the  stronger.  The  lines  from 
X  3930.450  toward  the  violet,  17  in  number,  are  with  one  exception  either  normal  triplets  or  have  the  separ- 
ation 30,  usually  the  latter.  Of  the  9  lines  showing  a  difference  greater  than  0.008  A,  3  are  normal  trip- 
lets and  4  have  a  separation  of  30.  The  question  of  dissymmetry  seems  worthy  of  investigation  through 
a  long  range  of  field-strengths  for  these  lines,  especially  to  test  the  generality  of  the  change  of  spacing 
with  the  square  of  the  field-strength  observed  for  one  of  the  lines  in  the  mercury  spectrum  (see  p.  5). 

An  element  which  might  sometimes  affect  the  spacing  of  Zeeman  components  is  the  apparent  differ- 
ence in  the  wave-lengths  of  arc  and  spark  lines.  The  spark  is  made  more  disruptive  by  the  magnetic 
field,  and  a  greater  disruptiveness  seems  in  general  to  cause  the  lines  of  the  spark  to  be  moved  slightly 
toward  the  red  as  compared  with  their  positions  in  the  arc  spectrum.  The  reality  of  this  effect  is  still 
a  disputed  question,  but  evidence  published  by  a  number  of  observers,  as  well  as  some  photographs  of 
the  arc  and  spark  which  I  have  taken  for  this  portion  of  the  iron  spectrum,  indicate  that  measurements 
taken  in  the  regular  way  will  give  a  slightly  greater  wave-length  for  the  spark  lines,  the  difference  being 
greatest  for  a  very  disruptive  spark.  If  this  effect  has  a  part  in  the  Zeeman  phenomenon,  we  should 
expect  all  components  of  the  triplet  to  be  displaced  alike.  The  greater  strength  of  the  middle  component, 
however,  would  probably  make  the  effect  more  perceptible  for  this,  as  the  apparent  displacement  is  more 
or  less  combined  with  unsymmetrical  widening  and  is  usually  more  distinct  for  strong  lines.  However, 
in  the  photographs  from  which  the  measurements  of  Table  6  were  taken,  triplets  to  the  violet  of  X  4000 
show  the  middle  component  only  about  as  strong  as  either  side  component  on  account  of  the  polariza- 
tion given  by  the  angle  of  the  grating  used,  so  that  the  conditions  of  the  spark  discharge  would  not  seem 
to  be  adequate  to  explain  the  difference  in  spacing,  unless  the  direction  of  vibration  of  the  electrons, 
parallel  or  perpendicular  to  the  lines  of  force,  affects  their  susceptibility  to  the  displacing  action  of  the 
spark  discharge.  On  this  point  we  have  no  evidence. 

The  other  point  of  dissymmetry  predicted  by  Voigt,  a  greater  strength  for  the  red  component  of  the 
triplet,  is  quite  perceptible  for  many  lines,  especially  in  the  iron  spectrum.  The  difference  is  rarely  greater 
than  10  per  cent.,  and,  to  be  clearly  detected,  the  two  components  must  be  distinct  but  not  of  full  density, 
since  blackness  of  the  components  in  the  negative  destroys  so  slight  a  difference.  On  account  of  this 
necessity  for  just  the  right  degree  of  exposure,  it  is  difficult  to  say  how  general  the  phenomenon  is,  but  it 
is  certainly  present  for  many  lines. 


LAW  OF  CHANGE  OF  THE  AVERAGE  SEPARATION  OF  THE  ^-COMPONENTS 

WITH  THE  WAVE-LENGTH. 

A  glance  through  Tables  i  and  2  shows  that  for  both  iron  and  titanium  the  tendency  is  for  the  values 
of  AX  gradually  to  increase  as  we  pass  to  greater  wave-lengths,  while  the  values  of  AX/X2  remain  of  about 
the  same  magnitude  throughout.  A  statistical  study  of  this  apparent  constancy  of  the  averages  AX/X2 
has  been  made;  and  both  the  range  of  wave-length  and  the  number  of  lines  available  are  sufficient  to 
show  clearly  how  the  matter  stands. 

The  method  of  treatment  has  been  to  obtain  the  mean  value  of  AX/X2  for  the  w-components  for  each 
500  A  from  X37oo  to  X67oo.  When  there  are  two  or  more  pairs  of  w-components  the  mean  of  the  separa- 
tions is  taken.  This  is  necessary  for  the  sake  of  consistency  if  any  lines  other  than  clear  triplets  or  quad- 
ruplets are  to  be  considered,  since  the  measurement  of  the  widened  «-components  given  by  a  great  many 
lines  is  merely  the  mean  separation  of  two  or  more  unresolved  pairs. 

The  averages  thus  obtained  are  presented  in  Table  7.  The  means  for  the  six  groups  of  500  A  are 
given  first,  then  the  means  for  the  three  groups  of  1000  A.  These  latter  are  the  means  for  the  whole 
number  of  lines  considered  in  the  range,  not  the  averages  of  the  means  for  the  5oo-groups.  Of  course, 
no  account  can  be  taken  in  this  summary  of  the  considerable  number  of  lines  which  are  described,  but 
whose  w-components  are  not  measurable. 

TABLE  7. — MEANS  or  AX/X2  (B-COMPONENTS)  FOR  SUCCESSIVE  REGIONS  OF  WAVE-LENGTH. 


IRON. 

TITANIUM. 

RANGE  OF  X 

No.  OF  LINES. 

MEAN  AX/X1. 

No.  OF  LINES. 

MEAN  AX/X2. 

3700-4200 

267 

2.003 

80 

1.009 

4200-4700 

IOI 

2.051 

152 

2.027 

4700-5200 

74 

2.123 

81 

.684 

5200-5700 

62 

1-932 

47 

.819 

5700-6200 

37 

1.837 

34 

.942 

6200-6700 

41 

2.131 

28 

.764 

3700-4700 

368 

2.016 

232 

.986 

4700-5700 

136 

2.037 

128 

•734 

5700-6700 

78 

1.989 

62 

1.862 

The  close  agreement  of  the  means  shows  that  there  is  a  real  relation,  giving  an  approximate  constancy 
of  the  values  of  AX/X2  for  different  parts  of  the  spectrum.  Taking  the  successive  means  of  the  5oo-groups, 
the  average  value  for  iron  is  2.013,  f°r  titanium  1.858.  The  largest  deviation  from  the  mean  for  any 
group  is  8.7  per  cent  for  iron  and  9.4  per  cent  for  titanium.  For  neither  element  is  there  any  systematic 
change  in  the  means  for  successive  groups. 

The  means  for  the  groups  of  1000  A  show  a  still  closer  agreement,  the  largest  deviation  from  the  mean 
of  these  groups  being  only  1.2  per  cent  for  iron  and  6.8  per  cent  for  titanium. 

It  will  be  noticed  that  the  mean  values  for  titanium  run  smaller  than  those  for  iron,  although  the 
titanium  measurements  correspond  to  the  larger  field-strength.  A  number  of  spectra  will  have  to  be 
examined  in  this  way  and  the  measurements  reduced  to  the  same  field-strength  before  we  can  say  what 
significance,  if  any,  there  is  in  this  point.  It  may  prove  to  be  connected  with  certain  properties  of  the 
elements  concerned. 

It  is  not  difficult  to  see  that  this  constancy  of  the  mean  value  of  AX/X2  depends  on  the  general  relation 
of  this  quotient  to  the  fundamental  interval  a,  and  that  it  results  from  the  fact  that  the  great  majority 

53 


54 


INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM 


of  the  separations  for  the  w-components  range  from  the  values  of  2a  to  30  and  that  the  various  values 
of  the  multiples  of  the  interval  are  more  or  less  uniformly  distributed  throughout  the  spectrum.  This 
was  shown  for  the  triplets  (p.  47),  the  greater  number  of  which  show  a  separation  greater  than  20.  The 
exceptional  large  and  small  values  for  triplets,  together  with  the  mean  separations  of  the  complex  lines, 
combine  to  form  a  fairly  definite  mean  which  holds  for  the  whole  range  of  spectrum  examined. 

Since  AX/X2  is  shown  to  be  very  nearly  constant,  it  may  be  said  that  for  the  spectra  of  iron  and  titanium,  and 
probably  for  spectra  in  general,  the  mean  separation  of  the  n-components  varies  as  the  square  of  the  wave-length. 

A  similar  rule  must  hold  for  the  ^-components,  since  it  was  shown  (pp.  48-49)  that  complex  lines  of 
the  same  structure  in  different  parts  of  the  spectrum  show  the  same  relation  to  the  interval  a. 

It  is  of  interest  to  note  that  a  computation  along  the  lines  of  that  carried  out  here,  but  different  in 
method  and  with  comparatively  little  material  at  disposal,  was  made  by  Mr.  Hale  (38)  in  his  comparison 
of  sun-spot  doublets  with  the  Zeeman  separations  on  some  preliminary  plates  made  by  the  author.  The 
mean  AX  for  a  number  of  iron  lines  in  the  blue  was  divided  by  the  square  of  the  mean  wave-length  for 
the  region  considered.  Measurements  for  lines  extending  from  the  green  into  the  red  were  treated  simi- 
larly. The  quotients  of  the  mean  AX  by  the  square  of  the  mean  X  for  the  two  regions  agreed  exactly. 
While  this  result  does  not  have  the  same  significance  as  the  comparison  of  the  mean  values  of  AX/X2,  it 
is  clearly  based  on  the  same  relation  for  the  rate  of  increase  of  AX  with  X. 


THE  EFFECT  OF  THE  MAGNETIC  FIELD  UPON  ENHANCED  LINES. 

In  my  former  paper  (51)  on  the  titanium  spectrum,  the  behavior  of  the  enhanced  lines  was  examined 
to  see  if,  as  a  class,  they  were  affected  by  the  magnetic  field  differently  from  the  non-enhanced  lines. 
The  various  types  of  separation  were  found  to  occur  in  about  the  same  proportion  for  the  enhanced  lines 
as  for  the  spectrum  in  general.  The  same  conclusion  was  arrived  at  by  Mr.  Babcock  (62)  for  the  enhanced 
lines  of  chromium  and  of  vanadium. 

Table  8  gives  the  numbers  of  enhanced  and  non-enhanced  lines  considered  both  as  to  type  and  magni- 
tude of  separation.  Here,  as  in  Table  3,  a  given  type  includes  both  the  clear  and  the  questioned  cases  for 
that  type  occurring  in  Tables  i  and  2. 

TABLE  8. — COMPARISON  OF  TYPES  or  SEPARATION  FOR  ENHANCED 
AND  NON-ENHANCED  LINES. 


CHARACTER  OF 
SEPARATION. 

IRON. 

TITANIUM. 

ENHANCED. 

NON- 
ENHANCED. 

ENHANCED. 

NON- 
ENHANCED. 

Unaffected  

o 
25 
4 

0 

8 
3 
3 

9 
368 
45 
7 
no 

34 
46 

0 

49 
S 

i 

'3 

i 

13 

4 
242 

23 

4 
64 
II 
28 

Triple  

Quintuple  

Sextuple  

Complex  

Total  

43 

619 

82 

376 

The  enhanced  lines  of  each  element  are  found  to  present  a  diversity  of  types.  The  enhanced  and 
non-enhanced  triplets  are  in  about  the  same  ratio  as  the  total  number  of  enhanced  and  non-enhanced 
lines,  both  for  iron  and  titanium,  this  ratio  being  about  i :  14  for  iron  and  about  1:5  for  titanium.  Those 
types  for  which  the  number  is  sufficient  to  give  the  comparison  some  weight  are  in  the  same  ratios.  There 
seems  to  be  no  undue  proportion  of  any  one  type  among  the  enhanced  lines,  considered  as  a  whole. 


EFFECT  OF  THE  MAGNETIC  FIELD  UPON  ENHANCED  LINES. 


55 


Since  the  triplets  appear  to  be  representative,  and  as  their  magnitudes  of  separation  can  be  handled 
most  readily,  Table  9  is  arranged  to  compare  the  values  of  AX/X2  for  enhanced  and  non-enhanced  triplets. 
Triplets  whose  separation  was  not  measurable  are  omitted,  as  are  some  non-enhanced  triplets  of  very 
large  separation,  larger  than  is  shown  by  any  enhanced  lines. 

TABLE  9. — VALUES  OP  AX/X2  FOR  ENHANCED  AND  NON-ENHANCED  TRIPLETS. 


IRON. 

TITANIUM. 

RANGE  OF  AX/X2. 

ENHANCED. 

NON- 
ENHANCED. 

ENHANCED. 

NON- 
ENHANCED. 

o—  i.o 

i 

2 

o 

9 

1.0-1.4 

3 

40 

6 

3° 

1.4-1.8 

7 

94 

26 

99 

1.8-2.2 

5 

93 

ii 

66 

2.2-2.6 

3 

84 

4 

26 

On  account  of  the  small  number  of  enhanced  lines  of  iron,  Table  9  serves  to  bring  out  little  more  than 
the  distribution  of  the  values  of  AX/X2.  More  enhanced  lines  are  available  for  titanium,  and  in  the  study 
of  these,  two  points  are  noteworthy:  the  absence  of  very  small  separations,  and  the  disproportionately 
large  number  of  enhanced  triplets  giving  values  from  1.4  to  1.8.  This  range  includes  the  normal  triplet 
at  about  1.6,  and  the  table  shows  that  the  separations  of  over  half  of  the  lines  in  question  are  close  to 
this  value.  This  is  due  in  part  to  a  condition  which  appears  to  be  the  only  respect  in  which  the  enhanced 
lines  are  in  a  class  by  themselves  as  regards  the  Zeeman  phenomenon.  In  the  region  from  3600  to  460x3, 
which  is  rich  in  enhanced  line's  for  titanium,  the  strongest  enhanced  lines  were  selected,  22  in  number. 
These  are  lines  showing  a  high  degree  of  enhancement  in  the  spark  and  are  as  a  rule  much  stronger  in 
the  spark  than  any  of  the  lines  characteristic  of  the  arc.  A  short  exposure  with  a  strongly  condensed 
spark  would  show  these  lines  almost  alone.  Of  these  22  lines  17  are  clear  triplets;  the  remaining  5,  with 
one  exception,  the  weakest  in  the  list,  are  of  more  complex  character,  These  lines,  with  their  intensity  on 
the  scale  here  used,  their  type  of  separation,  and  the  values  of  AX/X2  for  the  triplets,  are  given  in  Table  10. 

TABLE  10. — EFFECT  OF  THE  MAGNETIC  FIELD  UPON  THE  STRONGER  ENHANCED 
LINES  OF  TITANIUM. 


X 

INTENSITY. 

SEPARATION. 

AX/X2 

X 

INTENSITY. 

SEPARATION. 

AX/X2 

3685.339 

20 

Triple 

1.708 

4302.085 

5 

Sextuple 

3741-791 

10 

Triple 

1.878 

4308.081 

8 

Octuple 

3759-447 

20 

Triple 

2.038 

43I3-034 

8 

Sextuple 

3761.464 

10 

Triple 

1-463 

4338.084 

IO 

Triple 

1.312 

3900.681 

5° 

Triple 

1.787 

4395  •  201 

20 

Triple 

1.796 

3913.609 

20 

Triple 

1-43° 

4443-976 

15 

Triple 

1-509 

4163.818 

20 

Triple 

1.696 

4468.663 

15 

Triple 

1.702 

4172.066 

15 

Triple 

1.442 

4501-445 

IS 

Triple 

1.471 

4290.377 

IO 

? 

4549.808 

20 

Triple 

2.125 

4294.204 

IO 

Triple 

i  '958 

4563.939 

IO 

Triple 

1-325 

4300.211 

8 

? 

4572-156 

20 

Triple 

i  .526 

The  values  of  AX/X2  for  the  lines  in  Table  10  do  not  appear  to  be  as  closely  related  to  the  interval  a 
as  is  usual  among  a  like  number  of  triplets  taken  at  random.  The  measurements  are  usually  of  high 
weight,  the  photographs  being  made  with  self-induction  in  the  spark  circuit,  and  still  there  is  a  total 
lack  of  'normal  triplets,  the  values  of  AX/X2  being  scattered  rather  uniformly  from  1.3  to  2.1.  The  most 
we  can  conclude  is  that  for  titanium  the  strongest  enhanced  lines  tend  toward  the  triplet  type,  but  not 
toward  the  simplest  intervals  of  separation.  When  we  extend  the  comparison  to  the  weaker  enhanced 
lines,  many  of  which  are  of  considerable  strength  in  the  arc,  a  large  variety  of  types  appears,  with  none 
predominating. 


COMPARISON  OF  THE  RESULTS  FOR  THE  ZEEMAN  EFFECT  AND  FOR  PRESSURE 

DISPLACEMENT. 

A  summary  of  the  theories  on  the  possible  connection  between  magnetic  separation  and  pressure 
displacement  is  given  on  pp.  5-7.  The  data  now  at  hand  permit  a  considerable  extension  of  the  compari- 
son made  in  my  former  paper  (4°).  This  is  mainly  in  two  directions.  First,  photographs  of  titanium  arc 
spectra  under  pressure  made  in  this  laboratory  by  Mr.  H.  G.  Gale  have  materially  added  to  pressure 
measurements  for  this  substance.  Although  this  material  has  not  yet  been  published  by  Mr.  Gale,  he 
has  kindly  permitted  me  to  use  his  values  in  this  comparison.  Second,  spectra  given  by  the  electric 
furnace  under  pressure  have  recently  been  obtained  by  me,  and  the  preliminary  results  (63)  bear  on  one 
of  the  questions  involved  in  the  present  discussion. 

In  Tables  n  and  12  the  values  of  the  magnetic  separations  in  the  second  column  are  taken  directly 
from  Tables  i  and  2  respectively.  These  values  of  AX  are  for  the  w-components,  the  mean  being  taken 
when  there  are  two  or  more  pairs.  Numerous  changes  have  been  made  as  compared  to  the  former  paper 
on  this  subject,  due  to  better  photographs  being  available. 

The  measurements  of  pressure  displacements  expressed  in  Angstrom  units  are  taken  from  the  publi- 
cations of  Humphreys  (416)  and  of  Duffield  (64)  for  the  iron  spectrum.  For  titanium,  some  measurements 
are  given  by  Humphreys,  but  most  of  the  pressure  values  are  from  the  photographs  of  Gale.  The  meas- 
urements by  Humphreys  in  the  third  column  are  for  a  pressure  of  42  atmospheres,  his  other  measurements, 
for  69  and  101  atmospheres,  being  for  only  a  part  of  the  lines.  For  the  iron  spectrum,  the  displacements 
of  Duffield  for  41  atmospheres  are  given  in  the  fourth  column.  For  titanium,  the  measurements  of  Gale 
taken  for  9  atmospheres  total  pressure  were  multiplied  by  4.7  to  bring  them  to  the  same  order  as  those 
of  Humphreys,  assuming  a  direct  proportion  between  displacement  and  pressure.  Occasionally  a  line 
was  not  obtained  by  these  observers  for  the  given  pressures,  in  which  case  an  approximate  value  was 
deduced  from  the  measurement  for  some  other  pressure  and  is  accompanied  by  an  interrogation  point. 

TABLE  n. — ZEEMAN  SEPARATIONS  AND  PRESSURE  DISPLACEMENTS  FOR  IRON. 


X 

SEPA- 
RATION 
H  = 
16,000. 

DISPLACEMENT. 

RATIO  SEP. 
TO  DISPL. 

CLASSES  SEP.  1 

AND  DlSPL. 

X 

SEPA- 
RATION 

TT  

16,000. 

DISPLACEMENT. 

RATIO  SEP. 
TO  DISPL. 

"IdSIQ  ONV 

•dag  S3ssvi3 

42  ATM. 
(HUMPH- 
REYS.) 

41  ATM. 
(DUF- 
FIELD.) 

42  ATM. 
(HUMPH- 
REYS.) 

41  ATM. 
(DUF- 
FIELD.) 

3659-663 
3669.666 
3670.240 
3676.457 
3677.764 
3680.069 
3683.229 
3684.258 

3687.610 
3689.614 
3695.194 
3704.603 
3705  .  708 
3709.389 
3716.054 
3720.084 
3722.729 
3724.526 
3727.778 
3733.469 
3735.014 
3737-281 

0.176 
0.176 
0.261 
0.236 
0.167 
o.  296 
0.480 
0.170 
0.311 

0-373 
0.261 
0.319 
0-294 
0.312 
0.290 
0.268 
0.260 
0.256 
0.318 

0.315 
0.310 
0.254 

0.050 
0.050 
0.047 
0.050 
0.052 
0.062 
0.040 
0.053 
0.090 
0.084 
0.070 
0.046 
0.054 
0.095 
0.107 
0.047 
0.050 
0.054 

O.  IOO 

0.050 
0.092 
0.040 

3-54 
3-54 

5-55 
4-V 

3-21 

4-77 

12.00 
3-21 
3-46 
4-44 
3-73 
6-93 
5-44 
3.28 
2.71 
5-70 
5-20 

4-74 
3.18 
6.30 
3-37 
6.35 

S:S 
S:S 
S:S 
S:S 
S:S 
S:M 
L:S 
S:S 
M:M 
M:M 
S:M 
M:S 
S:S 
M:M 
S:L 
S:S 
S:S 
S:S 
M:M 
M:S 
M:M 
S:S 

3738.4S4 
3743-508 
3745-7I7 
3746.058 
3748.408 
3749.631 
3758-375 
3763.945 
3765.689 
3767-34I 
3788.046 

3795-147 
3798.655 
3799-693 
3805.486 
3813.100 

3815-987 
3820.586 
3824.591 
3826.027 
3827.980 
3834.364 

0.207 
0.318 
0.228 

0.214 
0.289 
0.269 
0.218 

0.228 

0.326 

0-325 
0.326 
0.326 

0.204 

0.203 
0.264 
0.282 

0.345 
0.274 

o.  225 
0.248 

0.078 
o.  100? 
0.050 
0.050 
0.040 
0.085 
0.090 
0.095 
0.106 
0.118 
0.090 
0.093 
0.085 
0.075 
0.092 
0.058 

O.IIO 

0.125 

0.040 
0.090 

O.IO2 
O.IIO 

2-65 
3-i8 
4.56 

5-35 
3-40 

2-99 
2.29 

2.15 

3^62 
3-49 
3.84 
4-35 

2.22 
3-50 
2.40 
2.26 
8.63 

3-04 
2.  2O 
2.25 

S:M 
M:M 
S:S 
0:S 
S:S 
S:M 
S:M 
S:M 
S:L 
0:L 
M:M 
M:M 
M:M 
M:M 
S:M 
S:S 
S:L 
S:L 
M:S 
S:M 
S:L 
S:L 

56 


COMPARISON  OF  RESULTS  FOR  ZEEMAN  EFFECT  AND  FOR  PRESSURE  DISPLACEMENT. 
TABLE  n. — ZEEMAN  SEPARATIONS  AND  PRESSURE  DISPLACEMENTS  FOR  IRON — Continued. 


57 


X 

SEPA- 
RATION 
H= 
16,000. 

DISPLACEMENT. 

EJJ 

«53 
QO 
So 
«  H 

CLASSES  SEP.  1 

AND  DlSPL.  I 

X 

SEPA- 
RATION 
H  = 
16,000. 

DISPLACEMENT. 

Sg 

tn  8 

20 
So 
f*H 

CLASSES  SEP. 

AND  DlSPL. 

42  ATM. 
(HUMPH- 
REYS.) 

41  ATM. 
(DUF- 
FIELD.) 

42  ATM. 
(HUMPH- 
REYS.) 

41  ATM. 
(DUF- 
FIELD.) 

3840.580 

3841.195 
3850.118 
3856.524 
3860.055 
3865.674 
3872.639 
3878.720 

3886.434 
3887.196 
3888.671 
3893.542 

3895.803 

3899.850 
3903.090 
3904.052 
3906.628 
3920.410 
3923.054 
3928.075 
3930.450 
3948.925 
3950.102 
3956.819 
3969.413 
3977.891 
3981.917 

3984.113 
3986.321 

3997.547 
3998  .  205 

4005  .  408 
4009  .  864 

4014.677 
4017.308 

4022.018 

4045.975 
4063  .  759 
4071.908 
4107.649 

4109.953 
4118.708 
4127.767 
4132.235 
4134.840 
4I43.S72 
4144.038 
4154.667 
4156.970 
4175.806 
4181.919 
4185.058 
4187.204 
4187.943 

4I9I.595 
4195.492 
4196.372 

4198.494 
4199.267 
4202.198 
4204.101 
4210.494 
4219.516 
4222.382 
4227.606 

0.221 
0.164 

0.341 
0.341 
0-343 
0.284 
0.346 
0.348 

0.335 
0.264 
0.269 
0-347 
0-349 
0.278 
0.233 
0-347 
0-349 
0-351 
0.352 
0.352 
0.234 
0.348 
0.289 

0-354 
0.441 
O.24O 

0.216 
0.196 
0.266 
o.  226 
0.461 

0.377 
0.250 

0-397 
0.272 
0.298 
0.269 
o.  170 

0-397 
0.285 
0.271 
0.196 
0.510 

0.303 
0.280 

0-393 
0-379 
0.367 
0.296 

0-339 
0.390 

0.395 
0.402 
0.402 
0.320 
0-359 
0.383 
0.276 

0.323 
0-373 
0.806 
0.284 

0-475 
0.309 

0.090 

O.IOO 

0.082 
0.038 
0.042 
0.103 
0.108 
0.044? 
0.056 
0.073 
0.089 
0.072 
0.030 
0.036 
0.095 
0.056 
0.050 
0.033 
0.032 
0.038 
0.047 
0.050 
0.066 
0.036 
0.089 
0.042 
0.060? 
0.085 
0.061 
0.048 
0.066 
0.103 
0.040 
0.050 
0.062 
0.037 
0.103 
0.107 
0.092 
0.060 
0.062 
0.085 

2.46 
1.64 

8.97 

8.12 

3-33 

2.63 
7.86 

6.21 

4.59 
2.97 

3-74 
1.16 
9.69 

2-93 
4.  16 
6.94 
10.58 
10.96 
0.92 

0.75 
4.68 

5-27 
8.03 

3-98 
10.98 
4.00 
2.54 
3.21 
5-54 
3-42 
4.48 
9.42 
5.00 
6.40 

7-35 
2.89 

2-51 
1.85 
6.62 
4.60 
3.19 
2-39 
4.86 

5-Si 

3-97 
4.41 

5-73 

4-55 
4.84 

9-75 
2.08 

o-93 
1.30 

3^78 
4.14 

6.22 
5-13 
3.84 

i-33 
0.72 

S:M 
S:M 
O:M 
M:S 
M:S 
M:L 
S:L 
M:S 
M:S 
M:M 
S:M 
S:M 
M:S 
M:S 
S:M 
S:S 
M:S 
M:S 
M:S 
M:S 
M:S 
S:S 
M:M 
S:S 
M:M 
L:S 
S:S 
S:M 
S:M 
S:S 
S:M 
L:L 
M:S 
S:S 
M:M 
S:S 
M:L 
S:L 
S:M 
M:S 
S:M 
S:M 
S:M 
L:L 
M:S 
S:M 
M:L 
M:M 
M:M 
S:M 
M:M 
M:S 
M:L 
L:L 
L:L 
M:L 
M:L 
M:L 
S:M 
M:M 
M:S 
L:L 
S:M 
L:L 
M:L 

4233-772 
4236.112 
4245.422 
4250.945 
4260.640 

427L934 
4282.566 
4294.301 
4299.410 
4308.081 
4315.262 

4325.939 
4337-216 
4352.908 
4367.749 
4369.941 
4376.107 
4383  .  720 

4404-927 
4407.871 
4408  .  582 

4415-293 
4422.741 
4427.482 
4430.785 
4442.510 
4443.365 
4447.892 
4454.552 
4459-301 
4461.818 
4466.727 
4476.185 
4494.738 
4528.798 

453L327 
4548.024 
4592.840 
4603  .  i  26 

4647-617 
4691.602 
4710.471 

4736.963 
4787.003 

4789.849 
4859.928 
4871.512 
4878.407 
4919.174 
5171.778 

5i95.ii3 
5269.723 
5328.236 
5371-734 
5397-344 
5405-989 
5429.911 

5434-740 
5447.130 
S4S5-834 
5497  -73S 
5501.683 
5507.000 
5615-87? 

0.532 
0.452 
0-493 
0.246 

0.423 
0.341 
0.310 
0.319 
0.406 
0.320 

0.517 
0.245 
0.264 
0.416 
0.311 
0.282 
0.424 
0.332 
o.334 
0.631 
0.488 
0-338 
0.293 
0.430 
0.719 
0.485 
0.170 
0.585 
o.445 
0.449 

0-435 
o.343 
0.306 
0.302 
0.358 
0.400 
0.311 
0.416 
0.566 
0.392 
0.358 
0.242 
0.426 
0.409 
0.352 
0.564 
0.336 
i  .092 
0.591 
0.521 

0.457 
0.501 
0.470 

0.413 
0.630 

0.341 
0.607 

0.568 
0.692 
1.040 

I.OOI 

1.026 
0.586 

0.240 
0.274 
0.060 
0.089 
0.246 
0.083 
0.043 
0.084 

0.370 

0.405 

2.22 

1.65 
8.22 
2.76 
1.72 
4.  II 
7.21 
3.80 
1.30 
3.56 
I4.36 
2.52 

2-93 

8.00 
5-18 

5-i3 
10.87 
2.66 
3-04 
3-Si 
3-05 
3-89 
4-Si 
7.82 
3-78 

2-55 
2.83 

3-25 
5-56 
2.81 

7.25 

6.12 

4-25 
1-51 
2.08 
5-32 

3-21 

3.78 

6.09 

5.60 

S-ii 

4  03 
S-oi 
5-38 
4.40 

1-45 
0.80 

2-73 
1-58 
6-95 
5-71 
6.04 
4.70 

4-35 
7.88 

3-4i 
7.14 

5-98 
6-59 
9-45 
10-54 
8.55 
7-33 

L:L 
L:L 
L:S 
S:M 
L:L 
M:M 
M:S 
M:M 
L:L 
M:M 
L:S 
S:M 
S:M 
L:S 
M:S 
S:S 
L:S 
M:L 
M:L 
L:L 
L:L 
M:M 
M:M 
L:S 
L:L 
L:L 
S:S 
L:L 
L:M 
L:L 
L:S 
M:S 
M:M 
M:L 
M:L 
L:M 
M:M 
L:L 
L:M 
M:M 
M:M 
S:S 
L:M 
L:M 
M:M 
L:L 
M:L 
L:L 
L:L 
L:M 
L:M 
L:M 
L:M 
L:M 
L:M 
M:M 
L:M 
O:L 
L:M 
L:L 
L:L 
L:M 
L:L 
L:M 

0.082 
0.177 
0.069 
0.056 
0.086 

0.313 
O.O6O 
0.041 

0.090 
0.036 
0.097 
0.090 
0.052 
0.060 
0.055 
0.039 
0.125 

O.IIO 

0.180 
0.160 
0.087 
0.065 

0.055 
o.  190 
0.190 
0.060 
o.  180 
0.080 
0.160 
0.060 
0.056 
0.072 

0.200 

0.172 
0.075 
0.097 

O.IIO 

0.093 

0.070 
0.070 
0.060 

0.085 
0.076 
0.080 

0.390 

0.420 
0.400 

0.375 

0.075 
0.080 
0.083 

O.IOO 

0.095 

0.080 

O.IOO 

0.085 

O.I  2O 

0.095 

0.105 

O.IIO 

0.095 

O.I  2O 

0.080 

0.082 
0.056 



0.060 
0.047 
O.o6o 
0.056 



0.078 
0.046 
0.043 

0.159 
0.164 
O.o6o 
0.172 

0.172 
0.039 
0.046 
0.042 

0.168 
0.172 
0.078 

0.082 
0.082 
0.086 

0.099 
0.082 
0.108 
0.086 
0.095? 
0.099 
0.086 
0.065 
0.065 

0.105 
0.055? 

0.116 

0.064? 

0.070? 
0.040 

0.047 
O.igo 

0.431 
0.310 

Large 
Large 
Large 
0.065 
0.078 
0.060 

o.i57 
0.078 

0.358 
0.431 

0.073 
0.071 

0.074 



58          INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 
TABLE  12. — ZEEMAN  SEPARATIONS  AND  PRESSURE  DISPLACEMENTS  FOR  TITANIUM. 


X 

SEPA- 
RATION 
H  = 
17,500- 

DISPLACEMENT. 

RATIO  SEP. 
TO  DISPL. 

CLASSES  SEP. 

AND  DlSPL. 

X 

SEPA- 
RATION 
H  = 
17,500. 

DISPLACEMENT. 

Si 

co  a 

g° 
£S 

CLASSES  SEP. 

AND  DlSPL. 

42  ATM. 
(HUMPH- 
REYS.) 

42  ATM. 

(GALE.) 

24  ATM. 
(HUMPH- 
REYS.) 

42  ATM. 

(GALE.) 

3900.681 

3904.926 
3913.609 
3914.477 
3921-563 
3924.673 

3926-465 
3930.022 
3947.918 
3948.818 
3956.476 
3958.355 
3962.995 
3964.416 
3981.917 
3982.630 
3989.912 
3998.790 
4009.079 

4009  .  807 

4012.541 
4024.726 
4028.497 
4035.976 
4055.189 
4060.415 
4064.362 

4065.239 
4078.631 
4082.589 

4112.869 
4151.129 
4159.805 
4163.818 
4171.213 

4172.066 
4186.280 

4203.620 

4272.701 

4276.587 
4278.390 
4281.530 
4282.860 
4285.164 
4286.168 
4287.566 
4289.237 
4290.377 
4291.114 
4294.204 

4295.914 
4298.828 
4299.410 
4299.803 
4300.211 
4300.732 
4301.158 
4302.085 
4306.078 

4313.034 
4314.964 

0.272 
0.240 
0.219 
o-352 
0.426 
0.292 
0.247 
0.362 
0.098 
0.186 
0.229 
0.287 
0.461 

0-359 
0.188 
0.469 
0.275 
0.317 
0.347 
0.086 
0.198 

0-394 
0.269 

0-354 
0-395 
0-395 
0.396 

0-395 
0-395 
0-398 
0.301 

0-305 
0.263 
0.294 

O.2IO 
0.251 
0.282 

0-457 
0.364 

0.443 
0.304 
0.664 
0.244 
0.566 
0.400 
O.42I 
0.370 
0.284 
0.441 
0.36l 

0.218 

0.430 
0.356 
0.367 
0.265 
0.350 
0.368 
0.367 
0.449 
0.424 

0.212 
0.085 
0.174 
O.O28 
O.Oig 
0.047 
0.235 
0.042 
0.028 
0.075 
0.047 
0.080 
0.042 
0.038 
0.094 

o.oig 
0.103 
0.113 
0.028 
0.038 
0.042 
0.038 
0.085 
0.244 
0.085 
0.075 
0.094 
0.047 
0.019 
0.061 
0.047 
0.207 
0.160 
0.179 
0.146 
0.188 
0.056 
0.179 
0.075 
0.136 
0.188 
0.061 
0.132 
0.160 
0.099 
0.118 
0.108 
0.216 
0.103 
0.136 
0.103 
0.118 
0.103 
0.103 
0.136 
0.099 
0.113 
0.160 
0.113 
0.216 
0.146 

1.28 
2.82 
1.26 
12.57 
22.42 

6.21 

1-05 
8.62 
3.50 
2.48 

4.87 

3-59 
10.98 

9-45 

2.00 
24.68 
2.67 
2.80 
12.39 
2.26 
4-71 
10.37 
3.16 

1-45 
4-65 
5-27 
4.21 
8.40 
20.79 
6.52 
6.40 

i-47 
i  .64 
1.64 
1.44 
1-34 
5-04 
2-55 
4.85 
3-26 
1.62 
1.09 
1-85 
3-54 
4.04 

3-57 
3-42 
1-31 
4.28 
2.65 

1.85 
4-17 
3-46 
2.70 
2.68 
3.10 
2.30 

3-25 
2.08 
2.90 

S:L 
S:M 
S:L 
M:S 
L:S 
S:S 
S:L 
M:S 
S:S 
S:M 
S:S 
S:M 
L:S 
M:S 
S:M 
L:S 
S:M 
M:M 
M:S 
S:S 
S:S 
M:S 
S:M 
M:L 
M:M 
M:M 
M:M 
M:S 
M:S 
M:M 
M:S 
M:L 
S:L 
S:L 
S:L 
S:L 
S:S 
L:L 
M:M 
L:L 
M:L 
L:M 
S:L 
L:L 
L:M 
L:M 
M:M 
S:L 
L:M 
M:L 
O:M 
S:M 
L:M 
M:M 
M:L 
S:M 
M:M 
M:L 
M:M 
L:L 
L:L 

4318.817 
4326.520 
4338.084 
4346.278 
4360.644 
4394.093 
4395.201 
4417.450 
4421.928 
4422.985 
4426.201 
4427.266 
4434.168 
4440.515 
4443.976 
4449-3!3 
4451.087 
4453.486 
4453.876 

4455.485 
4457.600 

4465.975 
4468  .  663 
4471.408 
4475.026 

4479.879 
4480.752 
4481.438 
4489.262 
4501.445 
4512.906 
4518.198 
4518.866 
4522.974 
4527.490 
4533.419 
4534-953 
4535-741 
4536.094 
4536.222 
4544.864 
4548.938 
4549.808 
4552-632 
4555-662 
4562.814 
4563.939 
4572.156 
4617.452 
4623.279 
4629.521 
4682.088 

4691-523 
4758.308 

47S9.463 
4841.074 
4981.912 
4991  .  247 
4999.689 
5007.398 
5013.479 

o.337 
0.403 
0.247 

0-453 
0.348 

0.325 
0-347 
0.381 
0.289 

o.377 
0.318 
0.312 

0-259 
0.270 
0.298 
0.388 
0.340 

0.210 
0.263 

0.351 
0.400 
0.481 
0.340 

0.601 
0.509 
0.829 
o.6n 
0.548 
0.612 
0.298 
0.501 
0.498 

O.22O 
0.502 

0.495 
0.469 

0.449 
0-424 
0.323 

0.502 
0.560 
0.440 
0.510 
0.506 

0-424 
0.276 
0.319 

0.404 

0-379 
0.527 

0-399 
0.441 
0.382 
0.430 
0.390 
0.481 
0.458 
0.413 
0-339 
0-455 

0.042 

8.02 

2.86 
2.78 
1.62 
1.90 
4.92 
2.94 
3-00 
1.61 

3-34 
2.61 
4.46 
1.49 

1.  01 

2.89 

3.29 
2.79 

1.15 

2.43 

1.82 

2.07 

3-94 
i-57 
6.75 
1.41 
6.28 
4-49 
4.85 
4.19 
1.38 
3.8o 
3-66 
2-34 
3-44 
3-75 
3.13 
2.81 
3.12 
2.86 

6.  27 
3-73 
1-95 
3-86 
3.83 

1.  12 

1.84 
1-36 
2.97 
3-21 

3.12 

5.18 

5-51 
5-70 
4.67 

13-44 
6.25 

3-39 
3-44 
2.26 

8.12 

M:S 
L:L 
S:M 
L:S 
M:L 
M:M 
M:M 
M:L 
S:L 
M:M 
M:M 
M:M 
S:L 
S:L 
S:M 
M:M 
M:M 
S:L 
S:M 
M:L 
L:L 
L:M 
M:L 
L:M 
L:L 
L:L 
L:L 
L:M 
L:L 
S:L 
L:L 
L:L 
S:M 
L:L 
L:L 
L:L 
L:L 
L:L 
M:M 
O:L 
L:L 
L:L 
L:L 
L:L 
L:L 
L:S 
S:L 
M:L 
L:L 
M:M 
L:L 
M:M 
L:M 
M:M 
L:M 
M:S 
L:M 
L:L 
L:M 
M:L 
L:S 

0.073 

0.141 
0.089 
0.028 
0.183 
0.066 
0.118 
0.127 
0.179 
0.113 

0.122 
O.O7O 
0.174 
O.I4I 
0.103 
O.II8 
O.I22 
0.183 

0.108 

0.193 
0.193 
O.  122 

0.216 

0.089 
0.362 
0.132 
0.136 
O.II3 
0.146 

o.  216 

0.132 
0.136 
0.094 
0.146 
0.132 
0.150 

0.160 
0.136 
0.113 
0.160 
0.136 
o.  150 
0.226 
0.132 
0.132 
0.038 
o.  150 

0.235 
0.136 
0.118 
0.169 



0.045 
0.030 
0.045 

0.024? 

0.056 

0.049 
0.047 
0.055 



0.176 
0.124 

0.080 

0.103 

0.087 



0.115 

O.IOO 

0.077 
0.080 
0.067 
0.092 
0.029 
0.077 
0-135 

0.120 

o.  150? 

0.056 

0.104 

O.IIO 



0.104 

COMPARISON  OF  RESULTS  FOR  ZEEMAN  EFFECT  AND  FOR  PRESSURE  DISPLACEMENT. 


59 


The  fifth  and  sixth  columns  contain  ratios  of  Zeeman  separation  to  pressure  displacement,  the  one 
numerical,  the  other  of  letters  denoting  the  order  of  magnitude.  In  the  numerical  ratios  for  iron  the 
values  of  Humphreys  are  used  for  the  sake  of  uniformity,  those  of  Duffield  for  an  almost  equal  pressure 
being  taken  when  a  line  was  not  measured  by  the  former.  In  the  case  of  titanium  the  values  of  Gale 
are  the  more  numerous  and  are  used  in  the  ratios  when  possible.  The  letters  S,  M  and  L  in  the  sixth 
column  stand  for  small,  medium  and  large  values,  respectively,  of  separation  and  displacement.  The 
limits  covered  by  these  classes  are  as  follows: 


SEPARATION. 

DISPLACEMENT. 

IRON. 

TITANIUM. 

S   . 

<o.3oo 
o  .  300-0  .  400 
>o.400 

<o.o6o 
0.060-0.100 

>O.IOO 

<  0.060 

0.060-0.125 

>O.I2S 

M  

L  .    . 

The  reasons  for  this  classification  are  given  later. 

The  question  as  to  whether  there  is  a  close  proportionality  between  magnetic  separation  and  pressure 
shift  is  decided  in  a  definite  manner  by  the  sixth  column  in  Tables  n  and  12,  giving  the  numerical 
ratio  of  separation  to  displacement.  The  separations  for  each  spectrum  are  taken  for  a  constant  field 
and  the  displacements  for  a  constant  pressure.  The  probable  errors  in  measurement  can  explain  only 
in  a  very  small  degree  the  larger  differences  in  these  ratios.  For  iron  the  ratio-values  run  from  0.72  to 
14.36,  for  titanium  from  1.05  to  22.42.  The  distribution  between  these  limits  is  such  that  any  range 
which  might  reasonably  be  assumed  as  due  to  poor  measurements  covers  but  a  fraction  of  the  lines. 
Thus  in  Table  n,  ratios  ranging  from  2.00  to  5.00  take  in  90  out  of  173  lines,  or  52  per  cent;  the  same 
range  for  titanium  includes  67  out  of  122  lines,  or  55  per  cent.  The  range  from  3.00  to  5.0x3  in  the  two 
spectra  covers  35  and  34  per  cent  respectively. 

The  lack  of  constancy  in  the  ratio  being  apparent,  the  question  arises  as  to  whether  there  is  any  real 
connection  between  separation  and  displacement.  A  broad  classification  of  the  values  in  order  of  magni- 
tude may  be  of  service  in  this  connection.  For  this  purpose  the  separation  and  displacement  values  are 
classified  as  small,  medium  and  large,  the  range  for  each  class  being  given  above.  The  ratios  showing 
the  comparative  magnitudes  of  separation  and  displacement  for  each  line  are  given  in  the  sixth  col- 
umn of  the  tables.  The  displacement  measures  for  titanium  run  in  general  larger  than  for  iron,  so  that 
a  higher  point  of  division  between  the  medium  and  large  classes  is  chosen.  The  following  summary  of 
the  data  will  show  to  what  extent  a  general  agreement  exists  between  the  Zeeman  and  pressure  phenomena. 

The  ratios  of  classes  from  Tables  n  and  12  enable  us  to  form  Table  13,  in  which  the  173  iron  and  122 
titanium  lines  are  placed  in  three  main  groups.  Group  i  consists  of  the  ratios  S  :  S,  M  :  M,  L:  L,  and 
shows  that  the  separation  and  displacement  for  the  corresponding  lines  are  relatively  of  the  same  order. 
Group  2  contains  those  lines  for  which  separation  and  displacement  are  not  in  the  same,  but  in  adjacent, 
classes;  while  for  Group  3  the  separation  and  displacement  are  of  very  different  magnitude,  one  small 
and  the  other  large.  Those  lines  which  show  no  Zeeman  effect,  but  distinct  pressure  displacement,  are  also 
in  Group  3,  the  letter  O  being  associated  with  S,  M,  or  L  according  to  the  magnitude  of  the  displacement. 

It  will  be  seen  that  44  per  cent  of  the  iron  lines  are  in  good  agreement  as  to  order  of  magnitude, 
44  per  cent  show  a  probable  discordance,  while  12  per  cent  strongly  contradict  the  hypothesis  of 
equality  of  relative  magnitude.  Titanium  shows  a  somewhat  larger  proportion  of  its  lines  in  poor  agree- 
ment as  to  separation  and  displacement.  This  indicates  clearly  that  the  two  phenomena  are  not  very 
closely  related  as  regards  size  of  one  increasing  with  size  of  the  other.  The  large  number  of  lines  in  Group 
2  renders  any  positive  conclusion  difficult  on  account  of  the  possible  influence  of  errors  of  measurement. 


6o 


INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 


Trials  with  other  limits  for  the  small,  medium  and  large  classes  have  shown  that  the  group  percentages 
are  not  materially  altered,  as  this  results  in  a  transfer  back  and  forth  of  lines  near  the  limits  chosen.  An 
attempt  to  reduce  Group  2  was  made  by  taking  all  those  lines  which  had  one  or  both  values  so  near  the 
limit  of  the  class  that  the  error  of  measurement,  if  in  the  favorable  direction,  might  have  put  the  two 
values  into  the  same  class  and  so  have  brought  the  line  into  Group  i .  Lines  of  complex  Zeeman  separa- 
tion were  also  treated  in  this  way;  35  iron  lines  were  thus  selected,  which  when  added  to  Group  i  as  given 
in  Table  13  raised  its  total  to  64  per  cent  of  the  whole.  This  number,  then,  may  be  in  fair  agreement  as 
to  order  of  magnitude,  while  the  remaining  36  per  cent  are  divergent  beyond  the  errors  of  measurement 
and  in  some  distances  widely  different.  This  last  device  is  of  course  not  a  fair  treatment  of  the  data, 
since  the  error  of  measurement  is  as  likely  to  move  the  values  wider  apart  as  closer  together,  and  if  the 
same  treatment  had  been  applied  to  the  lines  of  Group  i,  some  of  them  would  have  moved  into  Group  2. 
However,  giving  the  agreement  hypothesis  the  benefit  of  the  doubt,  the  proportions  of  64  and  36  per 
cent  appear  to  be  the  most  favorable  that  can  be  gotten  out  of  the  list  of  iron  lines. 

TABLE  13. — SUMMARY  OF  CLASSES. 


IRON. 

TITANIUM. 

RATIO  OF  MAG. 

No.  OF 
LINES. 

GROUP 
TOTAL. 

GROUP 
PERCENTAGE. 

RATIO  OF  MAG. 

No.  OF 
LINES. 

GROUP 
TOTAL. 

GROUP 

PERCENTAGE. 

Group  i 

s-s 

24 
29 

23 
27 

22 
13 
IS 

8 
8 

i 
i 

2 

) 

1 

J 

•    76 

v    77 

>•      20 

44 
44 

12 

Group  i 
S:S 

6 

21 
26 

12 
10 
12 
12 

IS 

6 

0 

I 
I 

I- 

1- 

•    23 

43 
38 

19 

M:M     

M:M  
L:L  

L-L 

Group  2 
S-M. 

Group  2 
S:M  

M-  S 

M:S  

M-L 

M:L  

L-M. 

L:M  

Group  3 
S-L 

Group  3 

L-S 

L:S  

o-s 

O:S  

O-M 

O:M  

O-L 

O:L  

In  Group  3  we  have  those  lines  for  which  either  separation  or  displacement  is  small  and  the  other 
large,  and  in  addition  4  lines  of  iron  and  2  of  titanium  which  appear  to  be  unaffected  by  the  magnetic 
field,  while  they  show  a  variety  of  displacements,  in  some  cases  large.  These  offer  examples  of  ability  to 
respond  to  one  displacing  agency  and  not  to  the  other. 

A  closer  quantitative  comparison  is  afforded  by  taking  the  average  separations  and  displacements  for 
large  groups  of  lines.  This  is  done  in  Tables  14  and  15.  The  method  in  forming  Table  14  was  to  make 
a  list  of  all  pressure  displacements  classified  as  small,  place  opposite  them  the  Zeeman  separations  for 
the  same  lines,  and  take  the  mean  of  each  list  for  comparison  of  the  magnitude  of  the  two  effects.  Means 
were  formed  in  the  same  way  for  lines  of  medium  and  large  displacement.  The  ratios  of  mean  separa- 
tion to  mean  displacement  can  then  be  compared.  In  obtaining  the  results  for  each  class,  means  were 
formed  for  the  lines  in  three  groups  according  to  wave-length.  The  whole  table  thus  gives  a  comparison 
of  the  means  for  the  several  groups,  and  also  an  indication  as  to  how  the  means  for  both  separation  and 
displacement  change  with  the  wave-length. 

Table  15  was  made  in  the  same  way  as  Table  14,  except  that  here  the  class  of  Zeeman  separation, 
small,  medium,  or  large,  was  taken  as  the  basis,  and  the  corresponding  pressure  displacements  used  for 
a  comparison  of  means. 


COMPARISON  OF  RESULTS  FOR  ZEEMAN  EFFECT  AND  FOR  PRESSURE  DISPLACEMENT. 
TABLE  14. — MEANS  OF  SEPARATION  AND  DISPLACEMENT  CLASSIFIED  ACCORDING  TO  AMOUNT  OF  DISPLACEMENT. 


6i 


IRON. 

TITANIUM. 

RANGE  OF 
X. 

No.  OF 
LINES. 

MEANS. 

RATIO 

SEP. 

DlSPL. 

RANGE  OF 
X. 

No.  OF 
LINES. 

MEANS. 

RATIO 
SEP. 

DlSPL. 

SEP. 

DlSPL. 

SEP. 

DlSPL. 

Displacement:  Small  J 

3660-4000 
4000-4500 
4500-5600 

35 
18 

i 

0.290 
0.361 
0.242 

0.046 
0.051 
0.060 

6.30 

7.08 

4-03 

3900-4000 
4000-4500 
4500-5000 

9 

10 

3 

o.339 
0.319 

0.423 

0.034 
0.038 

0.041 

9-97 
8.39 
10.32 

Total    of    lines    and    weighted 
means  

54 

0.313 

0.048 

6.52 

22 

0.340 

0.037 

9.19 

Displacement:  Medium    .  .  .  .  J 

3660-4000 
4000-4500 
4500-5600 

•3° 

22 
19 

0.272 
0.297 
0.478 

0.084 
0.080 

0.085 

3-24 
3.71 
5.62 

3900-4000 
4000-4500 
4500-5000 

6 
30 

9 

0.249 
0.378 
0.385 

0.092 

0.099 
0.093 

2.71 
3.82 
4.14 

Total    of    lines    and    weighted 

71 

0-335 

0.083 

4.04 

45 

0.362 

0.097 

3-73 

Displacement:  Large  J 

3660-4000 
4000-4500 
4500-5600 

8 
24 
9 

0.221 

0-452 
0.679 

O.IOQ 

0.207 
0.245 

2.03 

2.18 
2.77 

3900-4000 

4000-4500 
4500-5000 

3 
3i 
19 

0.246 

o.379 
0.446 

0.207 
0.175 
0.157 

1.19 
2.16 
2.84 

Total    of    lines    and    weighted 

41 

0.462 

0.196 

2.36 

53 

0.396 

0.170 

2-33 

TABLE  15. — MEANS  OF  SEPARATION  AND  DISPLACEMENT  CLASSIFIED  ACCORDING  TO  AMOUNT  OF  SEPARATION. 


IRON. 

TITANIUM. 

RANGE  OF 
X. 

No.  OF 
LINES. 

MEANS. 

RATIO 
SEP. 

DlSPL. 

RANGE  OF 
X. 

No.  OF 
LINES. 

MEANS. 

RATIO 
SEP. 

DlSPL. 

SEP. 

DlSPL. 

SEP 

DlSPL. 

Separation:  Small   •! 

3660-4000 
4000-4500 
4500-5600 

42 
18 

i 

0.240 
0.258 
0.242 

0.072 
0.077 
0.060 

3-33 
3-22 
4.03 

3900-4000 
4000-4500 
4500-5000 

ii 
J9 

3 

0.230 

0.247 
0.265 

0.107 
0.128 
0.153 

2.15 

i-93 
i-73 

Total    of    lines    and    weighted 

61 

0.246 

0.073 

3-37 

33 

0.243 

0.123 

1.98 

Separation:  Medium  « 

3660-4000 
4000-4500 
4500-5600 

28 

24 
8 

60 

o.337 
0.346 

0.356 

0.065 
0.098 
0.136 

5.18 

3-53 
2.62 

3900-4000 
4000-4500 
4500-5000 

4 
34 
7 

0.348 
0.360 
0.362 

0-359 

0.055 

0.114 

0.113 

6-33 
3.16 
3.20 

Total    of    lines    and    weighted 
means            .           

o.343 

0.088 

3-90 

45 

0.108 

3-32 

Separation  :  Large  •! 

3660-4000 
4000-4500 
4500-5600 

2 

23 
2O 

0.460 

0.495 
0.629 

0.041 
0.173 
0.137 

11.22 
2.86 
4-59 

3900-4000 
4000-4500 
4500-5000 

3 
18 

21 

0.452 
0.519 

0.471 

0.027 
0.138 
0.127 

1.67 
3-76 
3-71 

Total    of    lines    and    weighted 
means  

45 

0-553 

o.  151 

3.66 

42 

0.490 

0.125 

3-92 

62 


INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 


In  Table  14  the  ratios  of  classes  given  by  the  weighted  means  for  the  three  magnitudes  of  displace- 
ment are  M  :  S,  M  :  M,  and  L  :  L  for  both  iron  and  titanium.  Table  15  gives  for  the  three  magnitudes 
of  separation  the  ratios  S  :  M,  M  :  M,  L  :  L,  for  both  elements.  There  is  thus  good  agreement  as  to  magni- 
tudes except  for  the  first  class  in  each  table.  A  large  proportion  of  the  lines  for  this  class  come  from 
the  region  below  X4ooo  and  there  is  a  sufficient  scattering  of  high  values  for  both  separation  and  displace- 
ment to  put  the  means  into  different  classes  when  formed  in  this  way.  The  behavior  of  the  ratios  of 
weighted  means  in  the  two  tables  is  interesting.  Those  in  Table  15  decrease  very  nearly  in  the  ratio 
3  :  2  :  i  for  the  three  classes  in  the  iron  table,  and  about  9  :  4  :  2  for  titanium,  showing  that  the  displace- 
ments increase  in  size  much  faster  than  the  separations.  The  same  material  is  used  in  Table  15,  but  here  we 
find  an  approximate  constancy  for  iron  and  a  gradual  increase  for  titanium.  It  is  probable  that  the 
change  as  shown  in  Table  14  is  a  real  one  and  that  it  is  obscured  in  Table  15  by  the  large  difference  in 
range  of  values  of  separations  and  displacements.  The  limits  of  this  range  are  in  the  ratio  of  about  i  to 
3  for  the  separations  (omitting  a  few  extreme  values)  and  about  i  to  10  for  the  displacements.  Thus, 
in  Table  14,  when  the  displacements  are  grouped  so  as  to  increase  in  magnitude,  there  is  a  much  smaller 
variation  among  corresponding  values  of  separation  than  we  have  among  the  displacement  values  when 
the  separations  are  graded  as  in  Table  15.  The  widely  divergent  values  of  displacement  scattered  through 
Table  15  would  thus  act  to  make  the  ratios  of  means  more  or  less  discordant. 

A  classification  by  Duffield  (640)  may  be  used  in  comparing  the  displacements  measured  by  him  with 
the  corresponding  Zeeman  separations  for  iron.  He  forms  three  main  groups  according  to  amount  of 
displacement.  Table  16  gives  the  mean  separation  and  displacement  for  each  of  these  groups,  at  first 
singly,  then  combined  so  as  to  form  two  groups  with  more  lines  in  each. 

TABLE  16.- — MEANS  OF  SEPARATION  AND  DISPLACEMENT  FOR  DUFFIELD'S  DISPLACEMENT  GROUPS. 


No.  or  LINES. 

MEAN  SEP. 

MEAN  DISPL. 

CLASSES  SEP. 

AND   DlSPL. 

Group  I 
Unreversed   

26 

M-M 

Reversed 

M-  M 

Group  II  

6 

o  483 

o  168 

L-L 

Group  III 

L-  L 

Total  of  Group  I 

0.319 
o  068 

M-M 

Totals  of  Groups  I  and  II  

16 

0.431 

0.262 

L:L 

We  see  that  separation  and  displacement  are  of  the  same  order  of  magnitude  throughout.  In  the 
last  two  lines  the  larger  number  of  values  gives  means  of  higher  weight.  These  means  show  as  before 
that  a  much  larger  range  is  covered  by  the  displacements  than  by  the  separations. 

Two  additional  points  are  to  be  considered  in  this  comparison.  The  first  is  the  rate  of  increase  of 
the  two  effects  with  magnetic  field  and  pressure,  respectively.  Duffield  found  that  the  displacements  of 
lines  belonging  to  the  three  groups  treated  in  Table  16  have  very  different  rates  of  increase  with  increase 
of  pressure,  the  lines  of  Group  III  showing  the  most  rapid  change.  A  corresponding  phenomenon  in  the 
Zeeman  effect  would  mean  a  different  rate  of  increase  of  separation  with  field-strength  for  different  lines. 
We  are  not  certain  that  this  does  not  exist,  since  the  proportionality  of  separation  to  field-strength  has 
been  established  by  careful  measurement  for  only  a  very  few  lines,  but  no  evidence  of  a  difference  for 
different  sets  of  lines  has  thus  far  been  presented. 

The  second  point  is  the  relation  of  the  variation  of  separation  and  displacement  with  the  wave-length. 
In  Tables  14  and  15  the  division  into  regions  of  wave-lengths  shows  the  distribution  of  magnitudes  in 
these  regions.  Following  down  the  columns  headed  "No.  of  Lines"  in  each  table,  we  see  that  the  propor- 
tion of  small  values  for  both  separation  and  displacement  is  greater  in  the  region  of  short  wave-lengths. 


COMPARISON  OF  RESULTS  FOR  ZEEMAN  EFFECT  AND  FOR  PRESSURE  DISPLACEMENT.  63 

For  the  medium  and  large  values  in  each  table,  the  proportion  of  lines  increases  in  the  region  of  greater 
wave-length,  this  being  very  decided  for  the  "large"  group.  Thus  there  is  a  clear  increase  in  magnitude 
of  both  separation  and  displacement  as  the  wave-length  increases.  The  lines  here  compared  seem  to  be 
representative  of  the  spectrum,  as  the  same  relation  holds  in  the  complete  Zeeman  tables,  which  contain 
a  much  larger  number  of  lines  for  this  range  of  wave-length. 

When  pressure  measurements  of  high  accuracy  are  available  for  an  extended  region  of  wave-length, 
the  rate  of  variation  with  the  wave-length  will  appear,  and  the  closeness  of  agreement  with  the  relation 
found  for  iron  and  titanium,  namely,  that  the  magnetic  separation  increases  proportionally  with  the 
square  of  the  wave-length  (p.  54),  will  afford  strong  evidence  concerning  the  common  physical  basis 
of  the  two  phenomena.  An  attempt  at  a  comparison  of  this  sort  has  been  made  by  the  author  in  a  recent 
paper  (63)  on  the  effect  of  pressure  upon  electric-furnace  spectra.  The  displacements  of  iron  lines  given 
by  the  electric  furnace  for  a  pressure  of  9  atmospheres  were  measured  for  two  regions  1000  A  apart,  from 
\4O5o  10X4450  and  from  X5O5O  to  \545o.  The  list  for  the  latter  region  did  not  include  as  many  of  the 
weaker  lines,  whose  displacements  are  often  large,  as  was  available  for  the  blue  region,  so  that  a  compari- 
son of  the  means  of  all  displacements  would  not  have  been  fair.  It  seemed  best  to  limit  this  preliminary 
comparison  to  those  lines  in  each  region  which  show  the  same  general  behavior  in  various  light  sources. 
In  the  furnace  they  appear  at  low  temperatures  and  show  reversal  with  strong  widening  under  pressure. 
They  are  lines  which,  although  not  connected  by  series  relations,  show  such  similarity  in  their  response 
to  the  excitations  of  furnace,  arc,  and  spark  that  the  vibrating  particles  which  produce  them  can  be 
assumed  to  have  many  points  of  similarity. 

Fifteen  lines  of  this  character  in  the  blue  region  were  compared  with  nine  similar  lines  in  the  green. 
The  mean  pressure  displacement  for  the  two  sets  was  found  to  be  almost  identical,  being  0.058  A  for  the 
blue  and  0.060  A  for  the  green  lines.  The  magnetic  separations  of  the  same  lines,  taken  from  Table  i, 
give  mean  values  of  0.330  A  and  0.520  A,  respectively,  for  the  blue  and  green  regions,  an  increase  of  60 
per  cent  for  a  difference  of  wave-length  of  about  1000  A.  The  evidence  from  these  selected  lines  is,  there- 
fore, against  a  close  connection  between  the  magnetic  and  pressure  phenomena.  Measurements  for  the 
arc  under  pressure,  however,  show  a  more  frequent  occurrence  of  large  displacements  as  we  pass  toward 
greater  wave-lengths,  and  more  complete  measurements  will  show  the  rate  of  change. 

Summarizing  the  comparison  here  presented,  it  may  be  said  that  there  is  a  fair  agreement  between 
magnitude  of  magnetic  separation  and  pressure  displacement  for  the  lines  of  iron  and  titanium  when  the 
means  of  large  groups  are  considered.  The  number  and  character  of  the  lines  not  in  agreement,  however, 
show  that  the  correspondence  is  not  close  enough  to  justify  preferring  any  one  of  the  theories  for  the 
pressure  effect  on  this  ground,  or  to  predict  the  effect  upon  a  given  line  of  one  influence  from  that  observed 
for  the  other.  The  degree  of  concordance  which  we  have  could  perhaps  result  entirely  from  the  fact 
that  the  magnitude  of  each  effect  increases  with  the  wave-length.  This  does  not  prove  a  close  physical 
relation,  since  any  theory  of  the  pressure  effect  that  might  be  offered  would  probably  involve  a  change 
with  the  wave-length.  A  comparison  of  the  rates  of  change  of  the  two  effects  appears  to  be  a  more  prom- 
ising line  of  investigation  than  an  extension  of  the  method  followed  for  iron  and  titanium;  as  the  number 
of  lines  treated  for  those  spectra  is  sufficient  to  show  clearly  the  degree  of  correspondence. 


SUMMARY  OF  RESULTS. 

The  leading  features  in  this  investigation  may  be  summarized  as  follows: 

1.  The  effect  of  a  magnetic  field  upon  the  spark  spectra  of  iron  and  titanium  has  been  studied  for  a 
total  number  of  1120  lines  between  the  limits  \366o  and  X 6743.    The  character  of  the  magnetic  separa- 
tion is  given,  with  weighted  measurements  as  complete  as  was  permitted  by  the  magnetic  fields  available. 

2.  The  types  of  resolution,  ranging  from  lines  unaffected  by  the  magnetic  field  to  those  having  thirteen 
and  possibly  more  components,  have  been  classified  and  the  important  features  of  each  class  have  been 
discussed. 

3.  The  relation  of  the  measured  separations  to  the  "normal  interval" 

e     H 
a=—  •  - 

m  4irv 

has  been  studied  for  all  types  of  resolution.  A  large  majority  of  the  separations  of  triplets  and  quadru- 
plets show  a  close  relation  to  this  interval,  while  the  generality  with  which  the  more  complex  types  show 
the  spacing  of  their  components  to  be  simply  related  to  this  interval  indicates  a  full  confirmation  of 
Runge's  law. 

4.  Many  cases  of  "magnetic  duplicates,"  i.e.,  lines  exactly  similar  in  resolution,  with  the  same  inter- 
vals between  components,  have  been  found  among  the  more  complex  types,  indicating  close  similarity 
in  the  light  vibrations  which  give  rise  to  these  lines.    Large  groups  of  lines  showing  triplet  separation 
are  similar  in  this  respect. 

5.  The  large  range  of  wave-length  covered  has  made  it  possible  to  observe  the  rate  of  increase  of 
magnetic  separation  with  the  wave-length.     This  increase  is  such  that  the  mean  value  of  AX/X2  for  suc- 
cessive intervals  throughout  this  range  shows  a  close  approach  to  constancy  for  both  iron  and  titanium, 
with  no  systematic  variation.    The  conclusion  is  that  for  these  spectra  the  mean  separation  of  Zeeman 
components  varies  as  the  square  of  the  wave-length. 

6.  Cases  of  unsymmetrical  separation  of  Zeeman  components,  so  distinct  as  to  be  classed  as  abnormal, 
have  been  pointed  out.    The  theory  of  Voigt  concerning  a  slight  dissymmetry  in  the  intensity  and  spacing 
of  the  components  of  triplets  has  been  tested  for  a  number  of  iron  lines,  with  the  result  that  this  effect 
appears  to  be  real  in  many  cases,  although  some  lines  fail  to  show  such  a  difference. 

7.  The  enhanced  lines  of  the  two  elements  have  been  compared  with  those  showing  no  enhancement 
in  the  spark,  both  as  to  type  and  magnitude  of  separation.    The  only  difference  between  the  behavior 
of  the  two  classes  in  the  magnetic  field  appears  to  be  that  among  the  stronger  enhanced  lines  of  titanium 
the  triplet  type  strongly  predominates,  the  separations  usually  being  of  medium  amount  and  not  closely 
related  to  the  interval  a. 

8.  On  account  of  a  possible  similarity  between  the  actions  of  the  magnetic  field  and  of  pressure  around 
the  light  source  as  displacing  agencies,  a  detailed  comparison  has  been  made  of  the  magnetic  separations 
and  corresponding  pressure  displacements  for  these  spectra.    It  was  proved  that  a  close  correspondence 
does  not  exist,  but  there  is  a  general  agreement  as  to  magnitude  of  the  two  effects  when  the  means  for 
large  numbers  of  lines  are  considered. 

In  conclusion,  I  wish  to  acknowledge  my  great  obligations  to  Mr.  Hale  for  his  unfailing  support  and 
interest  in  the  equipment  and  development  of  the  physical  laboratory  and  for  much  advice  as  to  the 
conduct  of  the  investigations.  A  great  deal  of  credit  is  due  also  to  Miss  Wickham  and  to  Miss  Griffin 
for  ^their  careful  and  often  difficult  work  in  the  measurement  and  reduction  of  the  photographs.  The 
large  number  of  spectrograms  required  to  do  justice  to  the  iron  spectrum,  in  particular,  increased  the 
work  of  measurement  out  of  proportion  to  the  total  number  of  lines  treated. 
64 


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65 


66 


INFLUENCE  OF  A  MAGNETIC  FIELD  UPON  THE  SPARK  SPECTRA  OF  IRON  AND  TITANIUM. 


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PLATE  1 


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